Question

Amongst the following, the total no. of compound whose aq. Solution turn red litmus paper blue is______.
$KCN,K_2{SO}_4,({NH}_4{)}_2{C}_2{O}_4,NaCl,{Zn(NO}_3{)}_{2,}{FeCl}_3,K_2{CO}_3,N{H}_3{NO}_3,LiCN$

Answer 1

$KCN$ is basic as $K^{+}$ is neutral ion & $C{N}^{-}$ is a basic ion. $KCN$ is basic turning red litmus blue,

$K_{2}S{O}_4$ formed from $H_{2}S{O}_4$(acid) & $KOH$(base)

$\therefore K_{2}S{O}_4$ is a neutral salt.

$(N{H}_4{)}_2{C}_2{O}_4$ is a salt of weak base. So, it is basic turns red litmus blue.

$NaCl$ is salt of strong acid-strong base $\therefore NaCl$ is neutral.

$Zn\left(N{O}_3\right)2$ salt of strong acid-weak base.

So aqueous solution is acidic.

$FeC{l}_3$ salt of strong acid-weak base.

$\therefore$ aqueous solution is acidic.

$K_{2}C{O}_3$ is a strongly alkaline solution.

$N{H}_{4}N{O}_3$ salt of strong acid weakbase.

So, aqueous solution is acidic.

$LiCN$ is basic as $L{i}^{+}$ is neutral ion and $C{N}^{-}$ is basic ion.

$\therefore$ aqueous solution of $LiCn$ is basic.

So, no. of compounds whose aqueous solution turns red litmus red are $4$.

They are- $KCN$,$(N{H}_4{)}_2{C}_2{O}_4$,$K_{2}C{O}_3$ and $LiCN$