Concept:An acidic salt in water produces excess
H+ ions, turning blue litmus red.
Explanation:Sodium hydrogentetraoxosulphate (VI) is
NaHSO4.
It is an acid salt because it still contains ionisable hydrogen.
In water, it dissociates to produce
H+ ions, making the solution acidic.
Therefore, it turns blue litmus paper red.
The other salts are either normal salts or basic salts and do not produce an acidic solution.
Answer:B. Sodium hydrogentetraoxosulphate (VI)