In the esterification reaction of alcohols,which of the following occurs?

$CH_3-C(OH)(CH_3)-CH_3 \xrightarrow[cool]{Na_2Cr_2O_7} (P)$; Product $(P)$ in the reaction is

When vapours of ethanol are passed over platinised asbestos in excess of air,the compound formed is

In the Victor-Meyer's test,the colours given by $1^o$,$2^o$,and $3^o$ alcohols are respectively:

In which of the following $S_N1$ reactions will a racemic mixture form as the major product?

An alcohol $X$ $(C_4H_{10}O)$ on dehydration gives an alkene $(C_4H_8)$ as the major product,which on bromination followed by treatment with $Y$ gives an alkyne $C_4H_6$. The alkyne $C_4H_6$ does not react with sodium metal. What are $X$ and $Y$?