$A$ compound gives a positive test with $I_2/NaOH$ and is extracted from benzene by saturated $NaHSO_3$. It may be

Which one of the following gives a yellow precipitate with iodine and $NaOH$ solution?

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 |

Comment on the optical activity of the products. They are:

Calcium butanoate on heating followed by treatment with $1,2-$ethanediol in the presence of a catalytic amount of an acid,produces a major product which is

Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents:
$(i)$ $PhMgBr$ and then $H_3O^{+}$
$(ii)$ Tollens' reagent
$(iii)$ Semicarbazide and weak acid
$(iv)$ Excess ethanol and acid
$(v)$ Zinc amalgam and dilute hydrochloric acid