Question

Which of the following solution will have pH = 13?

• A. 2g NaOH in 500 mL solution
• B. 100 mL solution of 0.005 M $Ca(OH{)}_2$
• C. 100 mL solution of 0.1 N $Ca(OH{)}_2$
• D. 4 g NaOH in 500 mL solution

Answer 1

Answer: (A), (B)

The correct options are
A 2g NaOH in 500 mL solution
B 100 mL solution of 0.005 M $Ca(OH{)}_2$

$pH=-log\left[H^{+}\right]$

$pOH=14-pH=14-13=1$

$\Rightarrow \left[O{H}^{-}\right]=0.1M$

$2gNaOH$ in 500 mL solution

$\left[O{H}^{-}\right]=4/40\times 1000/100=0.1$M

100 mL solution of $0.005MCa(OH{)}_2$

$\left[O{H}^{-}\right]=2\times 0.005\times 1000/10=0.1$M

So, A and B option.