{2} ⊆ {{1},{2}}. Why is this statement considered false? I've been struggling with this discrete mathematics question. Any clarification would be awesome, thanks!
{2} ⊆ {{1},{2}}

By definition, $X \subseteq Y$ if every element of $X$ is also an element of $Y$.
In your case, $X = \{2\}$ and $Y = \{\{1\},\{2\}\}$. So $X$ has the single element $2$, which is not among the two elements $\{1\}$ and $\{2\}$ of $Y$. (Note that $2 \neq \{2\}$.)
