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[ { "idx": 1, "label": "0", "Question": "What is blockchain?", "Answer": "Blockchain is a distributed and immutable digital ledger technology that records transactions across multiple computers in a way that ensures the security and integrity of the data." }, { "idx": 2, "label": "0", "Question": "What is a cryptocurrency?", "Answer": "A cryptocurrency is a digital or virtual form of currency that uses cryptography for security. Bitcoin and Ethereum are examples of cryptocurrencies." }, { "idx": 3, "label": "0", "Question": "What is a smart contract?", "Answer": "A smart contract is a self-executing contract with the terms of the agreement directly written into code. They automatically execute when predefined conditions are met." }, { "idx": 4, "label": "0", "Question": "What is a blockchain node?", "Answer": "A blockchain node is a device or computer that participates in the blockchain network by validating and relaying transactions, as well as storing a copy of the blockchain." }, { "idx": 5, "label": "0", "Question": "What is a decentralized ledger?", "Answer": "A decentralized ledger is a ledger that is distributed across multiple nodes or computers, eliminating the need for a central authority or intermediary." }, { "idx": 6, "label": "0", "Question": "What is the difference between public and private blockchains?", "Answer": "Public blockchains are open to anyone and are permissionless, while private blockchains are restricted to specific participants and are permissioned." }, { "idx": 7, "label": "0", "Question": "What is consensus in blockchain?", "Answer": "Consensus is the process by which participants in a blockchain network agree on the validity of transactions and the order in which they are added to the ledger." }, { "idx": 8, "label": "0", "Question": "What is a blockchain fork?", "Answer": "A blockchain fork occurs when there is a divergence in the blockchain's transaction history, leading to the creation of two separate chains." }, { "idx": 9, "label": "0", "Question": "What is a cryptocurrency wallet?", "Answer": "A cryptocurrency wallet is a software or hardware tool that allows users to store, manage, and transact with their cryptocurrencies." }, { "idx": 10, "label": "0", "Question": "What is mining in blockchain?", "Answer": "Mining is the process by which new blocks are added to a blockchain through computational work, typically associated with proof-of-work consensus algorithms." }, { "idx": 11, "label": "0", "Question": "What is a 51% attack?", "Answer": "A 51% attack occurs when an entity or group gains control of more than 50% of a blockchain's mining power, potentially allowing them to manipulate the blockchain's transactions." }, { "idx": 12, "label": "0", "Question": "What is a hash function in blockchain?", "Answer": "A hash function is a mathematical algorithm that converts input data into a fixed-length string of characters, which is used to uniquely represent data in blockchain." }, { "idx": 13, "label": "0", "Question": "What is a private key?", "Answer": "A private key is a secret cryptographic key that is used to sign transactions and gain access to cryptocurrency holdings." }, { "idx": 14, "label": "0", "Question": "What is a public key?", "Answer": "A public key is a cryptographic key that is used to receive cryptocurrency transactions and is derived from the corresponding private key." }, { "idx": 15, "label": "0", "Question": "What is the double-spending problem in blockchain?", "Answer": "The double-spending problem is the risk of a digital currency being spent more than once. Blockchain solves this problem by maintaining a transparent transaction history." }, { "idx": 16, "label": "0", "Question": "What is a block reward in mining?", "Answer": "A block reward is a reward given to miners for successfully adding a new block to the blockchain. It typically consists of newly created cryptocurrency coins and transaction fees." }, { "idx": 17, "label": "0", "Question": "What is a fork in blockchain software?", "Answer": "A fork in blockchain software occurs when there is a change in the protocol rules, resulting in two different versions of the blockchain." }, { "idx": 18, "label": "0", "Question": "What is a token in blockchain?", "Answer": "A token is a digital asset that can represent various assets or utilities and is often built on top of an existing blockchain, like Ethereum." }, { "idx": 19, "label": "0", "Question": "What is the role of a blockchain explorer?", "Answer": "A blockchain explorer is a tool that allows users to view and search the contents of a blockchain, including transactions, addresses, and blocks." }, { "idx": 20, "label": "0", "Question": "What is a consensus algorithm?", "Answer": "A consensus algorithm is a set of rules and protocols that ensure agreement among participants in a blockchain network regarding the validity of transactions and the state of the ledger." }, { "idx": 21, "label": "0", "Question": "What is the difference between Bitcoin and Ethereum?", "Answer": "Bitcoin is primarily a digital currency, while Ethereum is a blockchain platform that supports the development of smart contracts and decentralized applications (DApps)." }, { "idx": 22, "label": "0", "Question": "What is a hard fork in blockchain?", "Answer": "A hard fork is a significant and non-backward-compatible change in the blockchain's protocol, resulting in the creation of a new blockchain that is not compatible with the old one." }, { "idx": 23, "label": "0", "Question": "What is a soft fork in blockchain?", "Answer": "A soft fork is a backward-compatible change in the blockchain's protocol, allowing nodes with older software to continue participating in the network." }, { "idx": 24, "label": "0", "Question": "What is a gas fee in Ethereum?", "Answer": "A gas fee is a small amount of cryptocurrency paid by users to compensate miners for processing and including their transactions in the Ethereum blockchain." }, { "idx": 25, "label": "0", "Question": "What is a node operator in a blockchain network?", "Answer": "A node operator is an individual or entity that runs a blockchain node, helping to maintain the network's security and integrity." }, { "idx": 26, "label": "0", "Question": "What is a Merkle tree in blockchain?", "Answer": "A Merkle tree is a data structure used to efficiently store and verify the integrity of transactions in a block by creating a hash tree of transaction data." }, { "idx": 27, "label": "0", "Question": "What is an ICO (Initial Coin Offering)?", "Answer": "An ICO is a fundraising method in which new cryptocurrency tokens or coins are sold to investors to raise capital for a blockchain project." }, { "idx": 28, "label": "0", "Question": "What is a DApp (Decentralized Application)?", "Answer": "A DApp is a software application that runs on a decentralized blockchain network, often with no central control or ownership." }, { "idx": 29, "label": "0", "Question": "What is a consensus node in a blockchain network?", "Answer": "A consensus node is a node in a blockchain network that actively participates in the consensus process to validate and agree on transactions." }, { "idx": 30, "label": "0", "Question": "What is a nonce in blockchain mining?", "Answer": "A nonce is a random number used by miners to search for a valid hash when attempting to add a new block to the blockchain." }, { "idx": 31, "label": "0", "Question": "What is a private blockchain consortium?", "Answer": "A private blockchain consortium is a group of organizations that collaborate to operate a private blockchain network for specific use cases." }, { "idx": 32, "label": "0", "Question": "What is a permissioned blockchain?", "Answer": "A permissioned blockchain restricts access to the network and requires users to obtain permission to join or participate." }, { "idx": 33, "label": "0", "Question": "What is a decentralized exchange (DEX)?", "Answer": "A decentralized exchange is a blockchain-based platform that allows users to trade cryptocurrencies directly with one another, eliminating the need for intermediaries." }, { "idx": 34, "label": "0", "Question": "What is a stablecoin?", "Answer": "A stablecoin is a type of cryptocurrency designed to have a stable value, often pegged to a fiat currency like the US dollar." }, { "idx": 35, "label": "0", "Question": "What is a token standard in Ethereum?", "Answer": "A token standard in Ethereum defines a set of rules and functions that must be followed to create and manage tokens on the Ethereum blockchain. Examples include ERC-20 and ERC-721." }, { "idx": 36, "label": "0", "Question": "What is a cold wallet in cryptocurrency?", "Answer": "A cold wallet is a cryptocurrency wallet that is not connected to the internet, providing enhanced security against online threats." }, { "idx": 37, "label": "0", "Question": "What is a hot wallet in cryptocurrency?", "Answer": "A hot wallet is a cryptocurrency wallet that is connected to the internet and is used for frequent transactions." }, { "idx": 38, "label": "0", "Question": "What is a whitepaper in blockchain?", "Answer": "A whitepaper is a document that outlines the details of a blockchain project, including its goals, technology, and implementation plans." }, { "idx": 39, "label": "0", "Question": "What is a 2FA (Two-Factor Authentication) in cryptocurrency security?", "Answer": "2FA is an additional layer of security that requires users to provide two different authentication factors, such as a password and a one-time code, to access their cryptocurrency accounts." }, { "idx": 40, "label": "0", "Question": "What is a block timestamp in blockchain?", "Answer": "A block timestamp is a record of the exact time when a block is added to the blockchain, helping to establish the order of transactions." }, { "idx": 41, "label": "0", "Question": "What is a node synchronization in blockchain?", "Answer": "Node synchronization is the process by which a new node in a blockchain network downloads and verifies the entire blockchain to stay up to date with the network." }, { "idx": 42, "label": "0", "Question": "What is the concept of \"immutability\" in blockchain?", "Answer": "Immutability in blockchain refers to the inability to change or delete recorded transactions, ensuring the integrity of the ledger." }, { "idx": 43, "label": "0", "Question": "What is a cryptographic hash?", "Answer": "A cryptographic hash is a one-way function that takes an input (data) and produces a fixed-size string of characters, often used for data integrity verification in blockchain." }, { "idx": 44, "label": "0", "Question": "What is a private key storage best practice?", "Answer": "Storing a private key securely, such as in a hardware wallet or cold storage, is a best practice to protect cryptocurrency holdings." }, { "idx": 45, "label": "0", "Question": "What is a 24-word recovery phrase in cryptocurrency wallets?", "Answer": "A 24-word recovery phrase is a mnemonic phrase used to recover a cryptocurrency wallet's private keys in case of loss or theft." }, { "idx": 46, "label": "0", "Question": "What is the purpose of a testnet in blockchain development?", "Answer": "A testnet is a separate blockchain network used for testing and development purposes, allowing developers to experiment without using real cryptocurrency." }, { "idx": 47, "label": "0", "Question": "What is a token burn in cryptocurrency?", "Answer": "A token burn is the intentional and irreversible destruction of a certain number of cryptocurrency tokens to reduce the total supply and potentially increase the value of the remaining tokens." }, { "idx": 48, "label": "0", "Question": "What is a public key infrastructure (PKI) in blockchain security?", "Answer": "PKI is a framework that uses public key cryptography to secure communications and authenticate users in a blockchain network." }, { "idx": 49, "label": "0", "Question": "What is a replay attack in blockchain?", "Answer": "A replay attack occurs when a malicious actor retransmits a legitimate transaction on a different blockchain, potentially causing unintended consequences." }, { "idx": 50, "label": "0", "Question": "What is the role of a miner's fee in blockchain transactions?", "Answer": "A miner's fee is a small payment made by the sender of a blockchain transaction to incentivize miners to prioritize and include the transaction in a block." }, { "idx": 51, "label": "0", "Question": "What is the purpose of gas in Ethereum transactions?", "Answer": "Gas in Ethereum transactions is used to measure the computational work required to execute a transaction. Users pay gas fees to cover the cost of this work." }, { "idx": 52, "label": "0", "Question": "What is a zero-knowledge proof in blockchain privacy?", "Answer": "A zero-knowledge proof is a cryptographic method that allows one party to prove to another party that they know a specific piece of information without revealing the information itself." }, { "idx": 53, "label": "0", "Question": "What is a DAO (Decentralized Autonomous Organization)?", "Answer": "A DAO is an organization represented by rules encoded as a computer program on a blockchain. It operates without centralized control and often manages assets or decisions." }, { "idx": 54, "label": "0", "Question": "What is a hard wallet backup in cryptocurrency?", "Answer": "A hard wallet backup refers to a physical copy or secure storage of a cryptocurrency wallet's private keys, often as a paper wallet or hardware wallet recovery phrase." }, { "idx": 55, "label": "0", "Question": "What is the role of a block explorer in analyzing blockchain data?", "Answer": "A block explorer allows users to view and analyze the data on a blockchain, including transaction history, addresses, and block details." }, { "idx": 56, "label": "0", "Question": "What is a sidechain in blockchain technology?", "Answer": "A sidechain is a separate blockchain that is interoperable with a main blockchain, allowing assets to be transferred between the two chains." }, { "idx": 57, "label": "0", "Question": "What is the concept of \"cryptography\" in blockchain security?", "Answer": "Cryptography is the use of mathematical techniques to secure information in blockchain, including encryption and digital signatures." }, { "idx": 58, "label": "0", "Question": "What is the purpose of a timestamp in blockchain transactions?", "Answer": "A timestamp in blockchain transactions provides a record of when a transaction was created or received, aiding in chronological order verification." }, { "idx": 59, "label": "0", "Question": "What is a multisignature (multisig) wallet in blockchain?", "Answer": "A multisignature wallet requires multiple private keys to authorize and complete a transaction, enhancing security and requiring multiple parties to approve transactions." }, { "idx": 60, "label": "0", "Question": "What is a permissionless blockchain?", "Answer": "A permissionless blockchain allows anyone to join the network, validate transactions, and participate in consensus without requiring prior approval." }, { "idx": 61, "label": "0", "Question": "What is the role of a block header in a blockchain block?", "Answer": "A block header contains essential information about a block, including its hash, timestamp, and reference to the previous block, among other data." }, { "idx": 62, "label": "0", "Question": "What is a token swap in blockchain projects?", "Answer": "A token swap is the process of exchanging one type of cryptocurrency token for another, often during a blockchain project's migration or upgrade." }, { "idx": 63, "label": "0", "Question": "What is a quantum-resistant blockchain?", "Answer": "A quantum-resistant blockchain is designed to withstand attacks from quantum computers, which have the potential to break traditional cryptographic algorithms." }, { "idx": 64, "label": "0", "Question": "What is the purpose of a consensus mechanism in blockchain?", "Answer": "A consensus mechanism is used to ensure that all participants in a blockchain network agree on the state of the ledger and the validity of transactions." }, { "idx": 65, "label": "0", "Question": "What is the concept of \"block size\" in blockchain?", "Answer": "Block size refers to the maximum amount of data that can be included in a single block of a blockchain, affecting transaction capacity and network scalability." }, { "idx": 66, "label": "0", "Question": "What is the role of a block reward halving in Bitcoin?", "Answer": "A block reward halving is an event in which the reward given to Bitcoin miners for adding a new block is reduced by half, occurring approximately every four years." }, { "idx": 67, "label": "0", "Question": "What is the role of a blockchain bridge?", "Answer": "A blockchain bridge is a technology that enables the transfer of assets or data between two different blockchain networks, fostering interoperability." }, { "idx": 68, "label": "0", "Question": "What is a blockchain oracle?", "Answer": "A blockchain oracle is a trusted external source of information that provides data to a smart contract on a blockchain." }, { "idx": 69, "label": "0", "Question": "What is a block interval in blockchain?", "Answer": "A block interval is the time it takes for a new block to be added to the blockchain, which can vary between different blockchain networks." }, { "idx": 70, "label": "0", "Question": "What is a blockchain consensus algorithm called Proof of Stake (PoS)?", "Answer": "PoS is a consensus algorithm where validators are chosen to create new blocks and validate transactions based on the number of cryptocurrency tokens they hold and are willing to \"stake\" as collateral." }, { "idx": 101, "label": "1", "Question": "What is a smart contract?", "Answer": "A smart contract is a self-executing contract with the terms of the agreement directly written in code. It automatically enforces and executes these terms." }, { "idx": 102, "label": "1", "Question": "Where are smart contracts typically deployed?", "Answer": "Smart contracts are typically deployed on blockchain platforms like Ethereum." }, { "idx": 103, "label": "1", "Question": "What is the main benefit of smart contracts?", "Answer": "The main benefit of smart contracts is their trustless and automated execution of agreements, eliminating the need for intermediaries." }, { "idx": 104, "label": "1", "Question": "What programming languages are commonly used to write smart contracts on Ethereum?", "Answer": "Solidity and Vyper are commonly used programming languages for Ethereum smart contracts." }, { "idx": 105, "label": "1", "Question": "What is the Ethereum Virtual Machine (EVM)?", "Answer": "The EVM is the runtime environment for executing smart contracts on the Ethereum network." }, { "idx": 106, "label": "1", "Question": "What is gas in the context of smart contracts?", "Answer": "Gas is a measure of computational work required to execute a smart contract. Users pay gas fees to miners to execute contracts." }, { "idx": 107, "label": "1", "Question": "How are smart contracts secured against vulnerabilities?", "Answer": "Smart contracts are secured against vulnerabilities through careful coding practices, audits, and testing." }, { "idx": 108, "label": "1", "Question": "What is the role of oracles in smart contracts?", "Answer": "Oracles provide external data to smart contracts, enabling them to interact with real-world information." }, { "idx": 109, "label": "1", "Question": "What is the purpose of a smart contract's constructor function?", "Answer": "The constructor function initializes a smart contract's state variables when it is deployed." }, { "idx": 110, "label": "1", "Question": "What are the differences between private and public smart contracts?", "Answer": "Private smart contracts are only accessible to specific parties, while public smart contracts are accessible by anyone on the blockchain." }, { "idx": 111, "label": "1", "Question": "How is ownership of a smart contract determined?", "Answer": "Ownership of a smart contract is determined by the address that deploys the contract. This address has special privileges." }, { "idx": 112, "label": "1", "Question": "What is the purpose of a fallback function in a smart contract?", "Answer": "A fallback function handles incoming ether transactions when no other function is specified." }, { "idx": 113, "label": "1", "Question": "How do smart contracts facilitate automated payments?", "Answer": "Smart contracts can automatically release funds based on predefined conditions being met." }, { "idx": 114, "label": "1", "Question": "What is a DAO (Decentralized Autonomous Organization) in the context of smart contracts?", "Answer": "A DAO is an organization represented by rules encoded as a smart contract, often governing decisions or asset management." }, { "idx": 115, "label": "1", "Question": "What is the purpose of an event in a smart contract?", "Answer": "An event in a smart contract is used to log and notify external consumers when specific actions occur within the contract." }, { "idx": 116, "label": "1", "Question": "What is a reentrancy attack on a smart contract?", "Answer": "A reentrancy attack occurs when an external contract maliciously calls a vulnerable contract's function repeatedly before it can complete its execution." }, { "idx": 117, "label": "1", "Question": "What is a token standard for smart contracts?", "Answer": "A token standard defines the rules and functions for creating fungible or non-fungible tokens on a blockchain." }, { "idx": 118, "label": "1", "Question": "What is the purpose of a modifier in a smart contract?", "Answer": "A modifier is used to add custom conditions or checks to functions in a smart contract." }, { "idx": 119, "label": "1", "Question": "What is the difference between a call and a delegate call in a smart contract?", "Answer": "A call sends a message to an external contract, while a delegate call executes the external contract's code as if it were part of the calling contract." }, { "idx": 120, "label": "1", "Question": "What is a multisignature wallet in the context of smart contracts?", "Answer": "A multisignature wallet requires multiple private key signatures to authorize and complete a transaction." }, { "idx": 121, "label": "1", "Question": "What is gas optimization in smart contract development?", "Answer": "Gas optimization aims to reduce the cost of executing a smart contract by optimizing the code and data structures." }, { "idx": 122, "label": "1", "Question": "How do smart contracts enable decentralized finance (DeFi)?", "Answer": "Smart contracts enable DeFi by automating financial transactions, lending, and other services without the need for traditional financial intermediaries." }, { "idx": 123, "label": "1", "Question": "What is the purpose of the 'msg.sender' variable in a smart contract?", "Answer": "'msg.sender' represents the address of the account that sent the current transaction to the smart contract." }, { "idx": 124, "label": "1", "Question": "How can you access the balance of an address in a smart contract?", "Answer": "You can access the balance of an address using 'address.balance' in Solidity." }, { "idx": 125, "label": "1", "Question": "What is a stablecoin in the context of smart contracts and cryptocurrencies?", "Answer": "A stablecoin is a cryptocurrency designed to maintain a stable value, often pegged to a fiat currency." }, { "idx": 126, "label": "1", "Question": "How do you make a smart contract upgradable?", "Answer": "Smart contracts can be made upgradable by using proxy contracts and storing the contract's state separately from its logic." }, { "idx": 127, "label": "1", "Question": "What is a hard fork in the context of smart contracts and blockchains?", "Answer": "A hard fork is a significant and non-backward-compatible change to a blockchain's protocol, often leading to the creation of a new blockchain." }, { "idx": 128, "label": "1", "Question": "What is a soft fork in the context of smart contracts and blockchains?", "Answer": "A soft fork is a backward-compatible change to a blockchain's protocol, allowing nodes that have not upgraded to continue functioning." }, { "idx": 129, "label": "1", "Question": "What is the purpose of the 'now' (or 'block.timestamp') variable in a smart contract?", "Answer": "'now' (or 'block.timestamp') represents the current timestamp in a smart contract and is often used for time-based functionality." }, { "idx": 130, "label": "1", "Question": "What are non-fungible tokens (NFTs) in the context of smart contracts?", "Answer": "NFTs are unique digital assets represented as tokens on a blockchain, often used for digital collectibles and ownership proof." }, { "idx": 131, "label": "1", "Question": "How do you handle exceptions and errors in a smart contract?", "Answer": "Smart contracts handle exceptions and errors using require, assert, and revert statements." }, { "idx": 132, "label": "1", "Question": "What is a decentralized application (DApp) in the context of smart contracts?", "Answer": "A DApp is an application that runs on a decentralized network, often utilizing smart contracts for functionality." }, { "idx": 133, "label": "1", "Question": "What is gas limit and gas price when interacting with smart contracts?", "Answer": "Gas limit is the maximum amount of gas allocated to a transaction, while gas price is the cost per unit of gas." }, { "idx": 134, "label": "1", "Question": "What is a token sale (ICO) in the context of smart contracts?", "Answer": "A token sale, also known as an Initial Coin Offering (ICO), is a fundraising method where tokens are sold to investors in exchange for cryptocurrency." }, { "idx": 135, "label": "1", "Question": "What is the role of governance in managing smart contracts?", "Answer": "Governance involves decision-making processes by token holders or stakeholders to make changes to a smart contract or protocol." }, { "idx": 136, "label": "1", "Question": "What is a flash loan in the context of smart contracts?", "Answer": "A flash loan is an uncollateralized and temporary loan obtained within a single transaction on a blockchain." }, { "idx": 137, "label": "1", "Question": "What is a chainlink oracle in the context of smart contracts?", "Answer": "Chainlink provides decentralized oracles that allow smart contracts to securely access real-world data." }, { "idx": 138, "label": "1", "Question": "What is the purpose of a 'view' or 'pure' function in a smart contract?", "Answer": "'view' and 'pure' functions in a smart contract do not modify the state and are used for read-only operations." }, { "idx": 139, "label": "1", "Question": "What is the purpose of a 'selfdestruct' function in a smart contract?", "Answer": "'selfdestruct' is used to destroy a smart contract and send its remaining ether to a specified address." }, { "idx": 140, "label": "1", "Question": "How do you handle token transfers in a smart contract?", "Answer": "You can handle token transfers by interacting with the ERC-20 or ERC-721 standard functions." }, { "idx": 141, "label": "1", "Question": "What is the difference between an ERC-20 and ERC-721 token standard?", "Answer": "ERC-20 tokens are fungible and interchangeable, while ERC-721 tokens are non-fungible and represent unique assets." }, { "idx": 142, "label": "1", "Question": "What is the role of a smart contract's storage and memory areas?", "Answer": "'storage' is used for persistent data, while 'memory' is used for temporary data within a function." }, { "idx": 143, "label": "1", "Question": "What is the purpose of 'require' and 'assert' in a smart contract?", "Answer": "'require' is used to check conditions and revert transactions if they are not met, while 'assert' is used for internal consistency checks." }, { "idx": 144, "label": "1", "Question": "How do you upgrade a smart contract while preserving its state?", "Answer": "You can upgrade a smart contract using a proxy pattern and migrating the contract's state." }, { "idx": 145, "label": "1", "Question": "What is a token burn in the context of smart contracts?", "Answer": "A token burn involves destroying a certain number of tokens to reduce the total supply, often to control inflation." }, { "idx": 146, "label": "1", "Question": "What is the purpose of a 'modifier' in a smart contract?", "Answer": "A modifier is used to add custom conditions or checks to functions in a smart contract." }, { "idx": 147, "label": "1", "Question": "How do you access the balance of a specific address in a smart contract?", "Answer": "You can access the balance of an address using 'address.balance' in Solidity." }, { "idx": 148, "label": "1", "Question": "What is a decentralized exchange (DEX) in the context of smart contracts?", "Answer": "A DEX is a cryptocurrency exchange that operates without a central authority, often using smart contracts to facilitate trades." }, { "idx": 149, "label": "1", "Question": "What is a token bridge in the context of smart contracts?", "Answer": "A token bridge is a technology that enables the transfer of tokens between two different blockchain networks." }, { "idx": 150, "label": "1", "Question": "What is a flash loan in the context of smart contracts?", "Answer": "A flash loan is an uncollateralized loan obtained within a single transaction on a blockchain." }, { "idx": 151, "label": "1", "Question": "What are the common security best practices for developing smart contracts?", "Answer": "Security best practices include code audits, testing, and using established patterns like OpenZeppelin." }, { "idx": 152, "label": "1", "Question": "What is the role of the 'gaslimit' property in a smart contract?", "Answer": "'gaslimit' specifies the maximum amount of gas that can be used for a transaction." }, { "idx": 153, "label": "1", "Question": "What is 'gas estimation' in the context of smart contracts?", "Answer": "Gas estimation involves predicting the amount of gas required for a transaction or contract execution." }, { "idx": 154, "label": "1", "Question": "What is 'event emission' in a smart contract?", "Answer": "Event emission is the process of logging specific occurrences or actions within a smart contract for external monitoring." }, { "idx": 155, "label": "1", "Question": "What is a decentralized autonomous organization (DAO) in the context of smart contracts?", "Answer": "A DAO is an organization represented by rules encoded as a smart contract, often governing decisions or asset management." }, { "idx": 156, "label": "1", "Question": "What is 'block.timestamp' in a smart contract?", "Answer": "'block.timestamp' represents the current timestamp in a smart contract and is often used for time-based functionality." }, { "idx": 157, "label": "1", "Question": "What are the advantages of using smart contracts for supply chain management?", "Answer": "Smart contracts can automate and enhance transparency in supply chain processes, reducing fraud and errors." }, { "idx": 158, "label": "1", "Question": "What is a 'multisignature wallet' in the context of smart contracts?", "Answer": "A multisignature wallet requires multiple private key signatures to authorize and complete a transaction." }, { "idx": 159, "label": "1", "Question": "What are the common vulnerabilities in smart contracts?", "Answer": "Common vulnerabilities include reentrancy attacks, integer overflows, and logic errors." }, { "idx": 160, "label": "1", "Question": "What is the purpose of the 'msg.data' variable in a smart contract?", "Answer": "'msg.data' contains the complete calldata of the current transaction, which can be used to extract function arguments." }, { "idx": 161, "label": "1", "Question": "What is a decentralized identity (DID) in the context of smart contracts?", "Answer": "A DID is a digital identifier that allows individuals to have control over their personal information and identity on a blockchain." }, { "idx": 162, "label": "1", "Question": "What is a token swap in the context of smart contracts?", "Answer": "A token swap is the process of exchanging one type of cryptocurrency token for another, often during a blockchain project's migration or upgrade." }, { "idx": 163, "label": "1", "Question": "What is a 'state channel' in the context of smart contracts?", "Answer": "A state channel is a mechanism for off-chain scaling, allowing participants to conduct transactions without frequent on-chain interactions." }, { "idx": 164, "label": "1", "Question": "What is 'gas optimization' in the context of smart contract development?", "Answer": "Gas optimization aims to reduce the cost of executing a smart contract by optimizing the code and data structures." }, { "idx": 165, "label": "1", "Question": "What is a 'commit-reveal' scheme in the context of smart contracts?", "Answer": "A commit-reveal scheme is a technique used in voting or other applications where participants first commit to their choices before revealing them." }, { "idx": 166, "label": "1", "Question": "How do you create a new instance of a smart contract?", "Answer": "You create a new instance of a smart contract by deploying it on the blockchain using the contract's constructor function." }, { "idx": 167, "label": "1", "Question": "What is the purpose of the 'view' and 'pure' function modifiers in a smart contract?", "Answer": "'view' and 'pure' function modifiers indicate that a function does not modify the contract state and is used for read-only operations." }, { "idx": 168, "label": "1", "Question": "What is a 'fallback' function in a smart contract?", "Answer": "A fallback function handles incoming transactions when no other function is specified and is often used for receiving ether." }, { "idx": 169, "label": "1", "Question": "What is the role of smart contracts in the Internet of Things (IoT)?", "Answer": "Smart contracts can facilitate automated and secure interactions between IoT devices and data exchange." }, { "idx": 170, "label": "1", "Question": "What is a token standard for fungible tokens in smart contracts?", "Answer": "ERC-20 is the most common token standard for fungible tokens in smart contracts." }, { "idx": 201, "label": "2", "Question": "What is Solidity?", "Answer": "Solidity is a programming language used for writing smart contracts on the Ethereum blockchain." }, { "idx": 202, "label": "2", "Question": "What is a smart contract in Solidity?", "Answer": "A smart contract is a self-executing contract with the terms of the agreement directly written in code. It automatically enforces and executes these terms." }, { "idx": 203, "label": "2", "Question": "What is Ethereum?", "Answer": "Ethereum is a blockchain platform that supports the development and execution of smart contracts and decentralized applications (DApps)." }, { "idx": 204, "label": "2", "Question": "How do you declare a variable in Solidity?", "Answer": "You declare a variable in Solidity using the `var`, `uint`, `int`, or other data types followed by the variable name." }, { "idx": 205, "label": "2", "Question": "What is the data type 'address' used for in Solidity?", "Answer": "The 'address' data type in Solidity is used to store Ethereum addresses, which can represent user accounts or other contracts." }, { "idx": 206, "label": "2", "Question": "What is a function in Solidity?", "Answer": "A function in Solidity is a reusable piece of code that performs a specific task when called." }, { "idx": 207, "label": "2", "Question": "How do you define a function in Solidity?", "Answer": "You define a function in Solidity using the `function` keyword, followed by the function name, parameters, and return type (if any)." }, { "idx": 208, "label": "2", "Question": "What is a constructor in Solidity?", "Answer": "A constructor in Solidity is a special function that is executed only once when a contract is deployed. It initializes contract state variables." }, { "idx": 209, "label": "2", "Question": "What is the purpose of the 'modifier' keyword in Solidity?", "Answer": "The 'modifier' keyword in Solidity is used to add custom conditions or checks to functions. It helps enforce access control and other requirements." }, { "idx": 210, "label": "2", "Question": "How do you comment code in Solidity?", "Answer": "You can comment code in Solidity using `//` for single-line comments or `/* */` for multi-line comments." }, { "idx": 211, "label": "2", "Question": "What is the 'fallback' function in Solidity?", "Answer": "The 'fallback' function in Solidity is a function with no name that is called when a contract receives ether without specifying a function to call." }, { "idx": 212, "label": "2", "Question": "What is 'gas' in Solidity and Ethereum?", "Answer": "Gas is a measure of computational work required to execute a transaction or contract on the Ethereum network. Users pay gas fees to miners." }, { "idx": 213, "label": "2", "Question": "How do you send ether to another address in Solidity?", "Answer": "You can send ether to another address in Solidity using the `transfer` or `send` method." }, { "idx": 214, "label": "2", "Question": "What is an 'event' in Solidity?", "Answer": "An event in Solidity is a way to log and notify external consumers when specific actions occur within a contract." }, { "idx": 215, "label": "2", "Question": "How do you define an event in Solidity?", "Answer": "You define an event in Solidity using the `event` keyword, followed by the event name and any parameters to log." }, { "idx": 216, "label": "2", "Question": "What is 'msg.sender' in Solidity?", "Answer": "'msg.sender' is a global variable in Solidity that represents the address of the account that sent the current transaction." }, { "idx": 217, "label": "2", "Question": "What is 'msg.value' in Solidity?", "Answer": "'msg.value' is a global variable in Solidity that represents the amount of ether sent with the current transaction." }, { "idx": 218, "label": "2", "Question": "What is 'view' and 'pure' in function declarations?", "Answer": "'view' indicates that a function does not modify contract state, and 'pure' indicates that it does not even read contract state." }, { "idx": 219, "label": "2", "Question": "What is 'mapping' in Solidity?", "Answer": "A 'mapping' in Solidity is a data structure used to associate keys with values, similar to a dictionary or hash table." }, { "idx": 220, "label": "2", "Question": "How do you create an array in Solidity?", "Answer": "You create an array in Solidity by specifying the data type followed by square brackets, e.g., `uint[] myArray`." }, { "idx": 221, "label": "2", "Question": "What is 'msg.data' in Solidity?", "Answer": "'msg.data' is a global variable in Solidity that contains the complete calldata of the current transaction." }, { "idx": 222, "label": "2", "Question": "What is 'block.timestamp' in Solidity?", "Answer": "'block.timestamp' is a global variable in Solidity that represents the timestamp of the current block." }, { "idx": 223, "label": "2", "Question": "What is an 'external' function in Solidity?", "Answer": "An 'external' function in Solidity can only be called from outside the contract and not from other functions within the contract." }, { "idx": 224, "label": "2", "Question": "What is a 'public' state variable in Solidity?", "Answer": "A 'public' state variable in Solidity automatically generates a getter function to allow external access to its value." }, { "idx": 225, "label": "2", "Question": "What is 'require' and 'assert' in Solidity?", "Answer": "'require' is used to check conditions and revert transactions if they are not met, while 'assert' is used for internal consistency checks." }, { "idx": 226, "label": "2", "Question": "How do you import external Solidity files?", "Answer": "You can import external Solidity files using the `import` statement." }, { "idx": 227, "label": "2", "Question": "What is 'address(this)' in Solidity?", "Answer": "'address(this)' represents the address of the current contract instance." }, { "idx": 228, "label": "2", "Question": "What is 'selfdestruct' in Solidity?", "Answer": "'selfdestruct' is a method that can be used to destroy a contract and send its remaining ether to a specified address." }, { "idx": 229, "label": "2", "Question": "What is 'keccak256' in Solidity?", "Answer": "'keccak256' is a cryptographic hash function used in Solidity to generate a unique hash from input data." }, { "idx": 230, "label": "2", "Question": "What is 'now' in Solidity?", "Answer": "'now' is an alias for 'block.timestamp' and represents the current timestamp in Solidity." }, { "idx": 231, "label": "2", "Question": "What is 'bytes' in Solidity?", "Answer": "'bytes' is a data type in Solidity used to store arbitrary binary data." }, { "idx": 232, "label": "2", "Question": "What is 'fallback' in Solidity?", "Answer": "'fallback' is a function that is executed when a contract receives a call without specifying a function to call. It is used for gas payment." }, { "idx": 233, "label": "2", "Question": "What is 'memory' and 'storage' in Solidity?", "Answer": "'memory' is a temporary storage location for data within a function, while 'storage' is a persistent storage location for data between function calls." }, { "idx": 234, "label": "2", "Question": "What is 'revert' in Solidity?", "Answer": "'revert' is used to revert the current transaction with an error message." }, { "idx": 235, "label": "2", "Question": "What is 'constant' in Solidity?", "Answer": "'constant' (or 'view' or 'pure') indicates that a function does not modify state and is used for read-only operations." }, { "idx": 236, "label": "2", "Question": "How do you create a new contract instance in Solidity?", "Answer": "You create a new contract instance by calling the contract's constructor function using the 'new' keyword." }, { "idx": 237, "label": "2", "Question": "What is a 'fallback function' in Solidity?", "Answer": "A fallback function is a function without a name that is called when a contract receives ether without specifying a function to call." }, { "idx": 238, "label": "2", "Question": "What is 'memory allocation' in Solidity?", "Answer": "Memory allocation in Solidity is the process of reserving memory space for variables, arrays, and data within a function." }, { "idx": 239, "label": "2", "Question": "What is 'gas limit' in Ethereum?", "Answer": "Gas limit is the maximum amount of gas that a user is willing to pay for a transaction. It determines the transaction's execution capacity." }, { "idx": 240, "label": "2", "Question": "What is 'gas price' in Ethereum?", "Answer": "Gas price is the cost per unit of gas paid by a user to miners for executing a transaction." }, { "idx": 241, "label": "2", "Question": "What is a 'modifier' in Solidity and how is it used?", "Answer": "A modifier in Solidity is a reusable piece of code that can be applied to multiple functions to add custom checks or conditions." }, { "idx": 242, "label": "2", "Question": "How do you perform mathematical operations in Solidity?", "Answer": "You can perform mathematical operations in Solidity using standard operators like '+', '-', '*', '/', and '%'." }, { "idx": 243, "label": "2", "Question": "What is 'external' visibility in function declarations?", "Answer": "'external' visibility indicates that a function can be called from outside the contract but not from within other functions in the contract." }, { "idx": 244, "label": "2", "Question": "What is 'internal' visibility in function declarations?", "Answer": "'internal' visibility indicates that a function can only be called from within the contract or derived contracts." }, { "idx": 245, "label": "2", "Question": "What is 'public' visibility in state variables?", "Answer": "'public' visibility for state variables generates a getter function to allow external access to the variable's value." }, { "idx": 246, "label": "2", "Question": "What is 'private' visibility in Solidity?", "Answer": "'private' visibility indicates that a function or state variable can only be accessed from within the same contract." }, { "idx": 247, "label": "2", "Question": "What is 'memory' allocation used for in Solidity?", "Answer": "'memory' is used to allocate temporary storage for variables and data within a function, and it is cleared when the function execution ends." }, { "idx": 248, "label": "2", "Question": "What is 'storage' allocation used for in Solidity?", "Answer": "'storage' is used to allocate persistent storage for state variables that need to be accessed across multiple function calls." }, { "idx": 249, "label": "2", "Question": "What is a 'gas refund' in Ethereum?", "Answer": "A gas refund in Ethereum is a mechanism that returns excess gas to the sender of a transaction, reducing the overall cost." }, { "idx": 250, "label": "2", "Question": "How do you prevent integer overflow in Solidity?", "Answer": "You can prevent integer overflow by using SafeMath libraries or by performing overflow checks in your code." }, { "idx": 251, "label": "2", "Question": "What is the purpose of the 'block.gaslimit' property in Solidity?", "Answer": "'block.gaslimit' returns the gas limit for the current block." }, { "idx": 252, "label": "2", "Question": "What is a delegate call in Solidity?", "Answer": "A delegate call is a mechanism that allows a contract to execute code from another contract while preserving the calling contract's storage and context." }, { "idx": 253, "label": "2", "Question": "What is a 'modifier' in Solidity and how is it used?", "Answer": "A modifier in Solidity is a reusable piece of code that can be applied to multiple functions to add custom checks or conditions." }, { "idx": 254, "label": "2", "Question": "How do you perform mathematical operations in Solidity?", "Answer": "You can perform mathematical operations in Solidity using standard operators like '+', '-', '*', '/', and '%'." }, { "idx": 255, "label": "2", "Question": "What is 'external' visibility in function declarations?", "Answer": "'external' visibility indicates that a function can be called from outside the contract but not from within other functions in the contract." }, { "idx": 256, "label": "2", "Question": "What is 'internal' visibility in function declarations?", "Answer": "'internal' visibility indicates that a function can only be called from within the contract or derived contracts." }, { "idx": 257, "label": "2", "Question": "What is 'public' visibility in state variables?", "Answer": "'public' visibility for state variables generates a getter function to allow external access to the variable's value." }, { "idx": 258, "label": "2", "Question": "What is 'private' visibility in Solidity?", "Answer": "'private' visibility indicates that a function or state variable can only be accessed from within the same contract." }, { "idx": 259, "label": "2", "Question": "What is 'memory' allocation used for in Solidity?", "Answer": "'memory' is used to allocate temporary storage for variables and data within a function, and it is cleared when the function execution ends." }, { "idx": 260, "label": "2", "Question": "What is 'storage' allocation used for in Solidity?", "Answer": "'storage' is used to allocate persistent storage for state variables that need to be accessed across multiple function calls." }, { "idx": 261, "label": "2", "Question": "What is a 'gas refund' in Ethereum?", "Answer": "A gas refund in Ethereum is a mechanism that returns excess gas to the sender of a transaction, reducing the overall cost." }, { "idx": 262, "label": "2", "Question": "How do you prevent integer overflow in Solidity?", "Answer": "You can prevent integer overflow by using SafeMath libraries or by performing overflow checks in your code." }, { "idx": 263, "label": "2", "Question": "What is the purpose of the 'block.gaslimit' property in Solidity?", "Answer": "'block.gaslimit' returns the gas limit for the current block." }, { "idx": 264, "label": "2", "Question": "What is a delegate call in Solidity?", "Answer": "A delegate call is a mechanism that allows a contract to execute code from another contract while preserving the calling contract's storage and context." }, { "idx": 265, "label": "2", "Question": "What is a 'fallback function' in Solidity?", "Answer": "A fallback function is a function without a name that is called when a contract receives ether without specifying a function to call." }, { "idx": 266, "label": "2", "Question": "What is 'gas limit' in Ethereum?", "Answer": "Gas limit is the maximum amount of gas that a user is willing to pay for a transaction. It determines the transaction's execution capacity." }, { "idx": 267, "label": "2", "Question": "What is 'gas price' in Ethereum?", "Answer": "Gas price is the cost per unit of gas paid by a user to miners for executing a transaction." }, { "idx": 268, "label": "2", "Question": "What is 'require' and 'assert' in Solidity?", "Answer": "'require' is used to check conditions and revert transactions if they are not met, while 'assert' is used for internal consistency checks." }, { "idx": 269, "label": "2", "Question": "What is 'constant' in Solidity?", "Answer": "'constant' (or 'view' or 'pure') indicates that a function does not modify state and is used for read-only operations." }, { "idx": 270, "label": "2", "Question": "How do you create a new contract instance in Solidity?", "Answer": "You create a new contract instance by calling the contract's constructor function using the 'new' keyword." } ]

[ { "idx": 71, "label": "0", "Question": "What is a blockchain token burn rate?", "Answer": "The token burn rate refers to the rate at which cryptocurrency tokens are intentionally destroyed or taken out of circulation, often to control inflation." }, { "idx": 72, "label": "0", "Question": "What is a decentralized identity (DID) in blockchain?", "Answer": "A DID is a digital identifier that allows individuals to have control over their personal information and identity on a blockchain." }, { "idx": 73, "label": "0", "Question": "What is a zero-knowledge proof in blockchain privacy?", "Answer": "A zero-knowledge proof is a cryptographic method that allows one party to prove to another party that they know a specific piece of information without revealing the information itself." }, { "idx": 74, "label": "0", "Question": "What is a DAO (Decentralized Autonomous Organization)?", "Answer": "A DAO is an organization represented by rules encoded as a computer program on a blockchain. It operates without centralized control and often manages assets or decisions." }, { "idx": 75, "label": "0", "Question": "What is a hard wallet backup in cryptocurrency?", "Answer": "A hard wallet backup refers to a physical copy or secure storage of a cryptocurrency wallet's private keys, often as a paper wallet or hardware wallet recovery phrase." }, { "idx": 76, "label": "0", "Question": "What is the role of a block explorer in analyzing blockchain data?", "Answer": "A block explorer allows users to view and analyze the data on a blockchain, including transaction history, addresses, and block details." }, { "idx": 77, "label": "0", "Question": "What is a sidechain in blockchain technology?", "Answer": "A sidechain is a separate blockchain that is interoperable with a main blockchain, allowing assets to be transferred between the two chains." }, { "idx": 78, "label": "0", "Question": "What is the concept of \"cryptography\" in blockchain security?", "Answer": "Cryptography is the use of mathematical techniques to secure information in blockchain, including encryption and digital signatures." }, { "idx": 79, "label": "0", "Question": "What is the purpose of a timestamp in blockchain transactions?", "Answer": "A timestamp in blockchain transactions provides a record of when a transaction was created or received, aiding in chronological order verification." }, { "idx": 80, "label": "0", "Question": "What is a multisignature (multisig) wallet in blockchain?", "Answer": "A multisignature wallet requires multiple private keys to authorize and complete a transaction, enhancing security and requiring multiple parties to approve transactions." }, { "idx": 81, "label": "0", "Question": "What is a permissionless blockchain?", "Answer": "A permissionless blockchain allows anyone to join the network, validate transactions, and participate in consensus without requiring prior approval." }, { "idx": 82, "label": "0", "Question": "What is the role of a block header in a blockchain block?", "Answer": "A block header contains essential information about a block, including its hash, timestamp, and reference to the previous block, among other data." }, { "idx": 83, "label": "0", "Question": "What is a token swap in blockchain projects?", "Answer": "A token swap is the process of exchanging one type of cryptocurrency token for another, often during a blockchain project's migration or upgrade." }, { "idx": 84, "label": "0", "Question": "What is a quantum-resistant blockchain?", "Answer": "A quantum-resistant blockchain is designed to withstand attacks from quantum computers, which have the potential to break traditional cryptographic algorithms." }, { "idx": 85, "label": "0", "Question": "What is the purpose of a consensus mechanism in blockchain?", "Answer": "A consensus mechanism is used to ensure that all participants in a blockchain network agree on the state of the ledger and the validity of transactions." }, { "idx": 171, "label": "1", "Question": "What is a token standard for non-fungible tokens (NFTs) in smart contracts?", "Answer": "ERC-721 is the most common token standard for non-fungible tokens (NFTs) in smart contracts." }, { "idx": 172, "label": "1", "Question": "What is a 'fork' in the context of blockchain and smart contracts?", "Answer": "A fork is a significant change in a blockchain's protocol or codebase, leading to different versions of the blockchain." }, { "idx": 173, "label": "1", "Question": "What is the role of 'block.number' in a smart contract?", "Answer": "'block.number' represents the current block number in a smart contract, allowing for block-specific logic." }, { "idx": 174, "label": "1", "Question": "How do you access the balance of a specific address in a smart contract?", "Answer": "You can access the balance of an address using 'address.balance' in Solidity." }, { "idx": 175, "label": "1", "Question": "What is 'slippage' in the context of decentralized exchanges (DEXs) and smart contracts?", "Answer": "Slippage refers to the difference between the expected and actual price of an asset during a trade on a DEX." }, { "idx": 176, "label": "1", "Question": "What is a 'timelock' contract in the context of smart contracts?", "Answer": "A timelock contract restricts certain functions or actions until a specified time has passed." }, { "idx": 177, "label": "1", "Question": "What is 'reentrancy' and how can it be mitigated in smart contracts?", "Answer": "Reentrancy is a vulnerability where an external contract maliciously calls a vulnerable contract's function repeatedly. It can be mitigated by using mutex locks and careful coding practices." }, { "idx": 178, "label": "1", "Question": "What is 'front-running' in the context of smart contracts and how can it be prevented?", "Answer": "Front-running is the practice of exploiting the order in which transactions are processed. It can be prevented through various mechanisms, including batched transactions." }, { "idx": 179, "label": "1", "Question": "What is a 'merkle tree' in the context of smart contracts and blockchain?", "Answer": "A Merkle tree is a data structure used to efficiently verify the integrity of data within a block or a set of data." }, { "idx": 180, "label": "1", "Question": "What is 'EIP' in the context of Ethereum and smart contracts?", "Answer": "EIP stands for Ethereum Improvement Proposal and is a standardized process for proposing and implementing changes to the Ethereum network." }, { "idx": 181, "label": "1", "Question": "What are 'cryptography' and 'hash functions' used for in smart contracts?", "Answer": "Cryptography and hash functions are used for secure data storage, authentication, and verifying the integrity of data in smart contracts." }, { "idx": 182, "label": "1", "Question": "What is 'off-chain' and 'on-chain' data in the context of smart contracts?", "Answer": "Off-chain data is data that is stored and processed outside the blockchain, while on-chain data is stored directly on the blockchain." }, { "idx": 183, "label": "1", "Question": "What is 'gas estimation' in the context of smart contracts and Ethereum transactions?", "Answer": "Gas estimation involves predicting the amount of gas required for a transaction or contract execution on the Ethereum network." }, { "idx": 184, "label": "1", "Question": "What is a 'commit-reveal scheme' in the context of smart contracts and voting?", "Answer": "A commit-reveal scheme is a technique used in voting where participants first commit to their choices secretly and then reveal them." }, { "idx": 185, "label": "1", "Question": "What are the advantages of using smart contracts in supply chain management?", "Answer": "Smart contracts can enhance transparency, traceability, and automation in supply chain processes." }, { "idx": 271, "label": "2", "Question": "What is a 'fallback function' in Solidity?", "Answer": "A fallback function is a function without a name that is called when a contract receives ether without specifying a function to call." }, { "idx": 272, "label": "2", "Question": "What is 'memory allocation' in Solidity?", "Answer": "Memory allocation in Solidity is the process of reserving memory space for variables, arrays, and data within a function." }, { "idx": 273, "label": "2", "Question": "What is 'selfdestruct' in Solidity?", "Answer": "'selfdestruct' is a method that can be used to destroy a contract and send its remaining ether to a specified address." }, { "idx": 274, "label": "2", "Question": "What is 'keccak256' in Solidity?", "Answer": "'keccak256' is a cryptographic hash function used in Solidity to generate a unique hash from input data." }, { "idx": 275, "label": "2", "Question": "What is 'now' in Solidity?", "Answer": "'now' is an alias for 'block.timestamp' and represents the current timestamp in Solidity." }, { "idx": 276, "label": "2", "Question": "What is 'bytes' in Solidity?", "Answer": "'bytes' is a data type in Solidity used to store arbitrary binary data." }, { "idx": 277, "label": "2", "Question": "What is 'fallback' in Solidity?", "Answer": "'fallback' is a function that is executed when a contract receives a call without specifying a function to call. It is used for gas payment." }, { "idx": 278, "label": "2", "Question": "What is 'memory' and 'storage' in Solidity?", "Answer": "'memory' is a temporary storage location for data within a function, while 'storage' is a persistent storage location for data between function calls." }, { "idx": 279, "label": "2", "Question": "What is 'revert' in Solidity?", "Answer": "'revert' is used to revert the current transaction with an error message." }, { "idx": 280, "label": "2", "Question": "What is 'constant' in Solidity?", "Answer": "'constant' (or 'view' or 'pure') indicates that a function does not modify state and is used for read-only operations." }, { "idx": 281, "label": "2", "Question": "How do you create a new contract instance in Solidity?", "Answer": "You create a new contract instance by calling the contract's constructor function using the 'new' keyword." }, { "idx": 282, "label": "2", "Question": "What is a 'fallback function' in Solidity?", "Answer": "A fallback function is a function without a name that is called when a contract receives ether without specifying a function to call." }, { "idx": 283, "label": "2", "Question": "What is 'memory allocation' in Solidity?", "Answer": "Memory allocation in Solidity is the process of reserving memory space for variables, arrays, and data within a function." }, { "idx": 284, "label": "2", "Question": "What is 'storage' allocation used for in Solidity?", "Answer": "'storage' is used to allocate persistent storage for state variables that need to be accessed across multiple function calls." }, { "idx": 285, "label": "2", "Question": "What is a 'gas refund' in Ethereum?", "Answer": "A gas refund in Ethereum is a mechanism that returns excess gas to the sender of a transaction, reducing the overall cost." } ]

[ { "idx": 86, "label": "0", "Question": "What is the concept of \"block size\" in blockchain?", "Answer": "Block size refers to the maximum amount of data that can be included in a single block of a blockchain, affecting transaction capacity and network scalability." }, { "idx": 87, "label": "0", "Question": "What is the role of a block reward halving in Bitcoin?", "Answer": "A block reward halving is an event in which the reward given to Bitcoin miners for adding a new block is reduced by half, occurring approximately every four years." }, { "idx": 88, "label": "0", "Question": "What is the role of a blockchain bridge?", "Answer": "A blockchain bridge is a technology that enables the transfer of assets or data between two different blockchain networks, fostering interoperability." }, { "idx": 89, "label": "0", "Question": "What is a blockchain oracle?", "Answer": "A blockchain oracle is a trusted external source of information that provides data to a smart contract on a blockchain." }, { "idx": 90, "label": "0", "Question": "What is a block interval in blockchain?", "Answer": "A block interval is the time it takes for a new block to be added to the blockchain, which can vary between different blockchain networks." }, { "idx": 91, "label": "0", "Question": "What is a blockchain consensus algorithm called Proof of Stake (PoS)?", "Answer": "PoS is a consensus algorithm where validators are chosen to create new blocks and validate transactions based on the number of cryptocurrency tokens they hold and are willing to \"stake\" as collateral." }, { "idx": 92, "label": "0", "Question": "What is a blockchain token burn rate?", "Answer": "The token burn rate refers to the rate at which cryptocurrency tokens are intentionally destroyed or taken out of circulation, often to control inflation." }, { "idx": 93, "label": "0", "Question": "What is a decentralized identity (DID) in blockchain?", "Answer": "A DID is a digital identifier that allows individuals to have control over their personal information and identity on a blockchain." }, { "idx": 94, "label": "0", "Question": "What is a zero-knowledge proof in blockchain privacy?", "Answer": "A zero-knowledge proof is a cryptographic method that allows one party to prove to another party that they know a specific piece of information without revealing the information itself." }, { "idx": 95, "label": "0", "Question": "What is a DAO (Decentralized Autonomous Organization)?", "Answer": "A DAO is an organization represented by rules encoded as a computer program on a blockchain. It operates without centralized control and often manages assets or decisions." }, { "idx": 96, "label": "0", "Question": "What is a hard wallet backup in cryptocurrency?", "Answer": "A hard wallet backup refers to a physical copy or secure storage of a cryptocurrency wallet's private keys, often as a paper wallet or hardware wallet recovery phrase." }, { "idx": 97, "label": "0", "Question": "What is the role of a block explorer in analyzing blockchain data?", "Answer": "A block explorer allows users to view and analyze the data on a blockchain, including transaction history, addresses, and block details." }, { "idx": 98, "label": "0", "Question": "What is a sidechain in blockchain technology?", "Answer": "A sidechain is a separate blockchain that is interoperable with a main blockchain, allowing assets to be transferred between the two chains." }, { "idx": 99, "label": "0", "Question": "What is the concept of \"cryptography\" in blockchain security?", "Answer": "Cryptography is the use of mathematical techniques to secure information in blockchain, including encryption and digital signatures." }, { "idx": 100, "label": "0", "Question": "What is the purpose of a timestamp in blockchain transactions?", "Answer": "A timestamp in blockchain transactions provides a record of when a transaction was created or received, aiding in chronological order verification." }, { "idx": 186, "label": "1", "Question": "What is a 'state channel' and how does it improve scalability in smart contracts?", "Answer": "A state channel allows participants to conduct off-chain transactions, reducing the load on the blockchain and improving scalability." }, { "idx": 187, "label": "1", "Question": "What is 'layer 2' scaling in the context of smart contracts and blockchains?", "Answer": "Layer 2 scaling solutions aim to improve the scalability of blockchains by processing transactions off-chain or through secondary layers." }, { "idx": 188, "label": "1", "Question": "What is a 'block explorer' and how is it used with smart contracts?", "Answer": "A block explorer is a tool that allows users to inspect and explore transactions, blocks, and smart contracts on a blockchain." }, { "idx": 189, "label": "1", "Question": "What is 'plasma' in the context of smart contracts and scalability?", "Answer": "Plasma is a proposed framework for achieving scalable and high-throughput smart contracts by creating secondary blockchains." }, { "idx": 190, "label": "1", "Question": "What is the role of 'block.timestamp' in a smart contract?", "Answer": "'block.timestamp' represents the current timestamp in a smart contract and is often used for time-based functionality." }, { "idx": 191, "label": "1", "Question": "How do smart contracts enable decentralized finance (DeFi) applications?", "Answer": "Smart contracts enable DeFi by automating financial transactions, lending, and other services without the need for traditional intermediaries." }, { "idx": 192, "label": "1", "Question": "What is 'reentrancy' and how can it be prevented in smart contracts?", "Answer": "Reentrancy is a vulnerability where an external contract maliciously calls a vulnerable contract's function repeatedly. It can be prevented using mutex locks and careful coding practices." }, { "idx": 193, "label": "1", "Question": "What is 'flash minting' in the context of smart contracts and DeFi?", "Answer": "Flash minting is a mechanism that allows users to temporarily mint and use a large amount of a token within a single transaction." }, { "idx": 194, "label": "1", "Question": "What is the role of 'block.number' in a smart contract?", "Answer": "'block.number' represents the current block number in a smart contract, allowing for block-specific logic." }, { "idx": 195, "label": "1", "Question": "What is 'proof of stake' (PoS) and how does it differ from 'proof of work' (PoW) in smart contracts and blockchains?", "Answer": "PoS is a consensus mechanism where validators are chosen to create new blocks based on the amount of cryptocurrency they hold and are willing to \"stake,\" whereas PoW relies on computational work." }, { "idx": 196, "label": "1", "Question": "What is a 'cryptography' and 'hash function' used for in smart contracts?", "Answer": "Cryptography and hash functions are used for secure data storage, authentication, and verifying the integrity of data in smart contracts." }, { "idx": 197, "label": "1", "Question": "What is 'front-running' in the context of smart contracts and how can it be prevented?", "Answer": "Front-running is the practice of exploiting the order in which transactions are processed. It can be prevented through various mechanisms, including batched transactions." }, { "idx": 198, "label": "1", "Question": "What is 'gas optimization' in the context of smart contract development?", "Answer": "Gas optimization aims to reduce the cost of executing a smart contract by optimizing the code and data structures." }, { "idx": 199, "label": "1", "Question": "What are 'smart contract audits' and why are they important?", "Answer": "Smart contract audits are thorough code reviews performed by security experts to identify vulnerabilities and ensure the security of a smart contract." }, { "idx": 200, "label": "2", "Question": "What is 'layer 2' scaling in the context of smart contracts and blockchains?", "Answer": "Layer 2 scaling solutions aim to improve the scalability of blockchains by processing transactions off-chain or through secondary layers." }, { "idx": 286, "label": "2", "Question": "How do you prevent integer overflow in Solidity?", "Answer": "You can prevent integer overflow by using SafeMath libraries or by performing overflow checks in your code." }, { "idx": 287, "label": "2", "Question": "What is the purpose of the 'block.gaslimit' property in Solidity?", "Answer": "'block.gaslimit' returns the gas limit for the current block." }, { "idx": 288, "label": "2", "Question": "What is a delegate call in Solidity?", "Answer": "A delegate call is a mechanism that allows a contract to execute code from another contract while preserving the calling contract's storage and context." }, { "idx": 289, "label": "2", "Question": "What is a 'modifier' in Solidity and how is it used?", "Answer": "A modifier in Solidity is a reusable piece of code that can be applied to multiple functions to add custom checks or conditions." }, { "idx": 290, "label": "2", "Question": "How do you perform mathematical operations in Solidity?", "Answer": "You can perform mathematical operations in Solidity using standard operators like '+', '-', '*', '/', and '%'." }, { "idx": 291, "label": "2", "Question": "What is 'external' visibility in function declarations?", "Answer": "'external' visibility indicates that a function can be called from outside the contract but not from within other functions in the contract." }, { "idx": 292, "label": "2", "Question": "What is 'internal' visibility in function declarations?", "Answer": "'internal' visibility indicates that a function can only be called from within the contract or derived contracts." }, { "idx": 293, "label": "2", "Question": "What is 'public' visibility in state variables?", "Answer": "'public' visibility for state variables generates a getter function to allow external access to the variable's value." }, { "idx": 294, "label": "2", "Question": "What is 'private' visibility in Solidity?", "Answer": "'private' visibility indicates that a function or state variable can only be accessed from within the same contract." }, { "idx": 295, "label": "2", "Question": "What is 'memory' allocation used for in Solidity?", "Answer": "'memory' is used to allocate temporary storage for variables and data within a function, and it is cleared when the function execution ends." }, { "idx": 296, "label": "2", "Question": "What is 'storage' allocation used for in Solidity?", "Answer": "'storage' is used to allocate persistent storage for state variables that need to be accessed across multiple function calls." }, { "idx": 297, "label": "2", "Question": "What is a 'gas refund' in Ethereum?", "Answer": "A gas refund in Ethereum is a mechanism that returns excess gas to the sender of a transaction, reducing the overall cost." }, { "idx": 298, "label": "2", "Question": "How do you prevent integer overflow in Solidity?", "Answer": "You can prevent integer overflow by using SafeMath libraries or by performing overflow checks in your code." }, { "idx": 299, "label": "2", "Question": "What is the purpose of the 'block.gaslimit' property in Solidity?", "Answer": "'block.gaslimit' returns the gas limit for the current block." }, { "idx": 300, "label": "2", "Question": "What is a delegate call in Solidity?", "Answer": "A delegate call is a mechanism that allows a contract to execute code from another contract while preserving the calling contract's storage and context." } ]