The number of possible alcoholic isomers for $C_4H_{10}O$ are

Based on which rule is $2$-butene obtained as the major product from the dehydration of $2$-butanol?

Product $(B)$ is

Give the structures of $A$,$B$,and $C$ in the following reaction:
$CH_3-CH_2-CH(OH)-CH_3$ $\xrightarrow{Cu, 520 \ K} (A)$ $\xrightarrow{C_2H_5MgBr} (B)$ $\xrightarrow{H_3O^+} (C)$

Find the correct order of boiling point among the following:

Which of the following would undergo dehydration most readily?