Hydrolysis of an ester gives a carboxylic acid,which upon Kolbe's electrolysis yields ethane. Identify the ester.

When compound $X$ is oxidised by acidified potassium dichromate,compound $Y$ is formed. Compound $Y$ on reduction with $LiAlH_4$ gives $X$. $X$ and $Y$ respectively are:

In the above reaction,identify the major product $(A)$ of the reaction.

In Column-$I$ formula,in Column-$II$ general name and in Column-$III$ $IUPAC$ name are given. Match the items in Column-$I$ with the appropriate items in Column-$II$ and Column-$III$.

Column-$I$ (Formula)	Column-$II$ (General Name) and Column-$III$ ($IUPAC$ Name)
$(A)$ $HCOOH$	$(i)$ Succinic acid,$(x)$ Methanoic acid
$(B)$ $CH_3CH_2CH_2COOH$	$(ii)$ Oxalic acid,$(y)$ Ethanedioic acid
$(C)$ $(COOH)_2$	$(iii)$ Formic acid,$(m)$ Butanedioic acid
$(D)$ $(CH_2)_2(COOH)_2$	$(iv)$ Butyric acid,$(n)$ Butanoic acid

The major product of the following reaction sequence is

What are $\underline{A}, \underline{B}, \underline{C}$ in the following reactions?
$(I)$ $(CH_3 CO_2)_2 Ca \stackrel{\Delta}{\longrightarrow} \underline{A}$
$(II)$ $CH_3 CO_2 H \underset{\text{Red P}}{\stackrel{HI}{\longrightarrow}} \underline{B}$
$(III)$ $2 CH_3 CO_2 H \stackrel{P_4 O_{10}}{\longrightarrow} \underline{C}$
$\underline{A} \quad \underline{B} \quad \underline{C}$