Lewis Acid-Base Concept. The Lewis theory classifies a substance as an acid if it acts as an electron-pair acceptor and as a base if it acts as an electron-pair donor. Other ways of classifying substances as acids or bases are the Arrhenius concept and the Bronsted-Lowry concept.ewis Acid-Base Concept. The Lewis theory classifies a substance as an acid if it acts as an electron-pair acceptor and as a base if it acts as an electron-pair donor. Other ways of classifying substances as acids or bases are the Arrhenius concept and the Bronsted-Lowry concept.
Microsoft Excel was created by Microsoft Corporation. It was first released in 1985.
Instructions. Click on the Windows âStartâ button then on âComputerâ to open Windows Explorer. Browse your computer to find the Excel file. Check the file extension. If it is .xlsx then the file was created with Excel 2007.The extension .xls indicates older program versions. Right-click on the Excel file and choose âPropertiesâ from the pop-up menu. Select the tab âDetailsâ (in Windows Vista or 7) or âSummaryâ then âAdvancedâ (in Windows XP).nstructions. Click on the Windows âStartâ button then on âComputerâ to open Windows Explorer. Browse your computer to find the Excel file. Check the file extension. If it is .xlsx then the file was created with Excel 2007.