CGPET 2018 Solved Paper

Formula of butane diol is $\mathrm{C}_4\mathrm{H}_{10}\mathrm{O}_2$. $\therefore$ It's molecular mass $=(4 \times 12)+(10 \times 1)+(2 \times 16)=90$ Given, mass of butane diol $(w)=0.9~\mathrm{g}$ $\therefore n=\frac{w}{m}=\frac{0.9}{90}=0.01~\mathrm{mol}$ where, $n=$ number of moles At STP, $n=\frac{\text{Volume of gas }(V)}{22.4~\mathrm{L}}$ $\therefore V=n \times 22.4~\mathrm{L}$ or $V=n \times 22400~\mathrm{mL}$ or $V=0.01 \times 22400$ or $V=224~\mathrm{mL}$ $\therefore (1)$ is the correct statement. 2. When 2 -iodobutane reacts with NaI, it gives alkyl di-iodide in which iodine atoms are attached with the $2^{\circ}$ -carbon. Thus, due to steric-hindrance it will undergo $\mathrm{S}_\mathrm{N}1$ reaction. Hence, we get racemic mixture. $\therefore$ Statement $(2)$ is correct. 3. Structure of 2 -methyl butane is as follows: $\overset{1}{\mathrm{C}}\mathrm{H}_3-\overset{2}{\underset{\mathrm{CH}_3}{\mathrm{C}}}\mathrm{H}-\overset{3}{\mathrm{C}}\mathrm{H}_2-\overset{4}{\mathrm{C}}\mathrm{H}_3$ $\because$ It has two similar groups, present on $\mathrm{C}_2$ carbon atom. It is not optically active. $\therefore$ Statement $(3)$ is wrong. 4. $\mathrm{C}_4\mathrm{H}_8$ does not show 7 -isomers, as it has only four carbon atoms. $\therefore$ Statement $(4)$ is wrong. $\therefore$ Option (c) is the correct option.