Question

You have three aqueous solutions A, B and C as given below:
A - Potassium nitrate
B - Ammonium chloride
C - Sodium carbonate
The ascending order of the pH of these solutions is:

• A. \( A<B<C \)
• B. \( B<C<A \)
• C. \( C<A<B \)
• D. \( B<A<C \)

Hint:

- Ammonium chloride produces an acidic solution in water. - Sodium carbonate produces a basic solution in water.

Answer 1

The Correct Option is B

The nature of a salt solution depends on the relative strengths of the parent acid and base.

• Ammonium chloride (B): It is formed from a strong acid (HCl) and a weak base (NH₄OH). Hence, its aqueous solution is acidic and has pH < 7.
• Potassium nitrate (A): It is formed from a strong acid (HNO₃) and a strong base (KOH). Therefore, its aqueous solution is neutral with pH ≈ 7.
• Sodium carbonate (C): It is formed from a weak acid (H₂CO₃) and a strong base (NaOH). Hence, its aqueous solution is basic and has pH > 7.

Therefore, the ascending order of pH is: 

B < A < C 

Answer: B < A < C