What is glycerol?

Statement-$1$ : Secondary $\&$ Tertiary alcohols can be distinguished by Lucas reagent.
Statement-$2$ : Secondary $\&$ Tertiary alcohols can be distinguished by dichromate test.

Which of the following is the structure of an alcohol with molecular formula $C_5H_{12}O$?

Optically active $3-$methylpent$-1-$en$-3-$ol loses its optical activity after standing in water containing a few drops of acid,mainly due to the formation of:

Which of the following compounds is used as an antifreeze agent in automobile radiators?

What are $X$ and $Y$ in the following reactions?