Question

To make a solution of pH = 12, the amount of NaOH dissolved in one litre of the solution should be –

• A. 0.1 g
• B. 0.2 g
• C. 0.4 g
• D. 1.2 g

Answer 1

Answer: (C)

0.4 g

Answer 2

pH = 12 means [H⁺] = 10^–12

or [OH^–] = 10^–2 M

or [NaOH] = 10^–2 M = $\frac{M}{100}$= $\frac{1}{100}$ × 40 g L^–1 = 0.4 g L^–1.