Consider the following reaction:
$\text{Propanal} + \text{Methanal}$ $\xrightarrow[\text{(ii)}\Delta, \text{(iii)}\text{NaCN}, \text{(iv)}\text{H}_3\text{O}^+]{\text{(i)}\text{dil. NaOH}} \text{Product } B (C_5H_8O_3)$
The correct statement for product $B$ is:

Which of the following pairs of compounds can be differentiated by $NaHCO_3$ as well as by $NaOH$?

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

Match Column-$I$ with Column-$II$ :
| Column-$I$ | Column-$II$ |
| :--- | :--- |
| $(A)$ Cyclopentanone + $2,4-$$DNP$ $\xrightarrow{\text{mild } H^+}$ Cyclopentanone$-2,4-$$DNP$ derivative | $(P)$ Electrophilic substitution |
| $(B)$ $4-$phenyl$-2-$methylbutan$-2-$ol $\xrightarrow{\text{Conc. } H_2SO_4}$ $1,1-$dimethyl$-1,2,3,4-$tetrahydronaphthalene | $(Q)$ Nucleophilic substitution |
| $(C)$ $4-$chlorocyclohexanethiol $\xrightarrow{\text{Base}}$ $7-$thiabicyclo[$2.2$.$1$]heptane | $(R)$ Nucleophilic addition |

Which of the following compounds on hydrolysis gives reactant $(A)$?

Give plausible explanation for each of the following:
$(i)$ Cyclohexanone forms cyanohydrin in good yield but $2,2,6-$trimethylcyclohexanone does not.
$(ii)$ There are two $-NH_2$ groups in semicarbazide. However,only one is involved in the formation of semicarbazones.
$(iii)$ During the preparation of esters from a carboxylic acid and an alcohol in the presence of an acid catalyst,the water or the ester should be removed as soon as it is formed.