Glycerol reacts with conc. $HNO_3$ and conc. $H_2SO_4$ to form

Which of the following can be used to test the acidic nature of ethanol?

Which of the following hydroxy ethers gives a $+ve$ test with Tollen's reagent?

$CH_3CH_2OH$ $\xrightarrow{Red \ P + I_2} (A)$ $\xrightarrow[Ether]{Mg} (B)$ $\xrightarrow{HCHO} (C)$ $\xrightarrow{H_2O} (D)$
The compound $(D)$ is

$C_2H_5Br$ $\xrightarrow{aq.\,NaOH} X$ $\xrightarrow[H_2SO_4]{Na_2Cr_2O_7} Y$
$[Y]$ is

Compound $A$ of molecular formula $C_4H_{10}O$ on treatment with Lucas reagent at room temperature gives compound $B$. When compound $B$ is heated with alcoholic $KOH$,it gives isobutene. Compound $A$ and $B$ are respectively: