Q. Among the following the compounds which can undergo an $S_{N}1$ reaction in an aqueous solution, are:

1. I and IV only
2. II and IV only
3. II and III only
4. II, III and IV only

Q. The major product of the following reaction is:

Q. Permanent hardness of water can be removed by:

1. heating
2. treating with sodium acetate $\left(C{H}_{2}C{O}_{2}Na\right)$
3. treating with $Ca(HC{O}_3{)}_2$
4. treatment with sodium hexametaphosphate $(N{a}_6{P}_6{O}_{18}$)

Q. Alkali metals (M) dissolve in liquid $N{H}_3$ to give:

1. $MN{H}_2$
2. $MH$
3. $\left[M\right(N{H}_3{)}_x{]}^{+}+\left[e\right(N{H}_3{)}_y{]}^{-}$
4. $M_{3}N$