Q19 / 84 · JEE Advanced 2010 (Paper 1) · Chemistry
Amongst the following, the total number of compounds whose aqueous solution turns red litmus paper blue is
$$
\begin{array}{llll}
\mathrm{KCN} & \mathrm{K}_2 \mathrm{SO}_4 & \left(\mathrm{NH}_4\right)_2 \mathrm{C}_2 \mathrm{O}_4 & \mathrm{NaCl} \\
\mathrm{Zn}\left(\mathrm{NO}_3\right)_2 & \mathrm{FeCl}_3 & \mathrm{~K}_2 \mathrm{CO}_3 & \mathrm{NH}_4 \mathrm{NO}_3 \\
\mathrm{LiCN} & & &
\end{array}
$$
Correct answer: 3
Solution
The aqueous solution of $\mathrm{KCN}, \mathrm{K}_2 \mathrm{CO}_3$ and LiCN turn red litmus blue because of alkaline nature.
The anionic hydrolysis turns the solution alkaline.
Ionic equilibrium
Conceptual
III
Hence, the correct answer is 3.