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KCET · Chemistry · Ionic Equilibrium

Which one of the following salts on being dissolved in water gives \(\mathrm{pH}>7\) at \(25^{\circ} \mathrm{C}\) ?

  1. A \(\mathrm{KCN}\)
  2. B \(\mathrm{KNO}_{3}\)
  3. C \(\mathrm{NH}_{4} \mathrm{Cl}\)
  4. D \(\mathrm{NH}_{4} \mathrm{CN}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(\mathrm{KCN}\)

Step-by-step Solution

Detailed explanation

\(\mathrm{KCN}\) is a salt of weak acid and strong base hence, on being dissolved in water it gives basic solution i.e. \(\mathrm{pH}>7\) at \(25^{\circ} \mathrm{C}\).
\[ 2 \mathrm{H}_{2} \mathrm{SO}_{4}+2 \mathrm{P}_{2} \mathrm{O}_{5} \longrightarrow 2 \mathrm{SO}_{3}+\quad 4 \mathrm{HPO}_{3} \] Sulphur trioxide