The products formed in the following reaction,$A$ and $B$ are

You have two $C_6H_{10}O$ ketones,$I$ and $II$. Both are optically active,but $I$ is racemized by treatment with acid and $II$ is not. Wolff-Kishner reduction of both ketones gives the same achiral hydrocarbon,formula $C_6H_{12}$. What reasonable structures may be assigned to $I$ and $II$ respectively?

In the following table,Column-$I$ shows the structure of a compound,Column-$II$ shows its $IUPAC$ name,and Column-$III$ shows its common name. Match the $IUPAC$ name and common name for each structure given in Column-$I$.
| Column-$I$ (Structure) | Column-$II$ ($IUPAC$ name) | Column-$III$ (Common name) |
| :--- | :--- | :--- |
| $(A)$ $C_6H_4(CHO)_2$ (ortho) | $(i)$ Benzophenone | $(p)$ Acrolein |
| $(B)$ $(CH_3)_2C=CHCOCH_3$ | $(ii)$ Benzene$-1,2-$dicarbaldehyde | $(q)$ Diphenyl ketone |
| $(C)$ $CH_2=CH-CHO$ | $(iii)$ Prop$-2-$enal | $(r)$ Phthaldehyde |
| $(D)$ $(C_6H_5)_2CO$ | $(iv)$ $4-$methylpent$-3-$en$-2-$one | $(s)$ Mesityl oxide |

In the following reaction:
$HC \equiv CH \xrightarrow[{Hg^{2+}}]{{H_2SO_4}} 'P'$
Product $'P'$ will not give:

The end product in the following sequence of reaction is
$HC \equiv CH$ $\xrightarrow{1\% \, HgSO_4, 20\% \, H_2SO_4} A$ $\xrightarrow{CH_3MgX} B$ $\xrightarrow{[O]}$

Acetone on addition to methyl magnesium bromide forms a complex,which on decomposition with acid gives $X$ and $Mg(OH)Br$. Which one of the following is $X$?