Question

What is the $pH$ of the $NaOH$ solution when $0.04g$ of it dissolved in water and made to $100mL$ solution?

• A. 2
• B. 1
• C. 13
• D. 12

Answer 1

Answer: (D)

Molecular mass of

$NaOH=23+16+1=40$

Molarity $=\frac{\text{ Mass of solute }(\text{ in }g)\times 1000}{\text{ Molecular mass of the solute }}\times$ Volume of solution (in L)

$=\frac{0.04\times 1000}{40\times 100}=10^{-2}$

$O{H}^{-}=10^{-2}mol/L$

So, $pOH=-\log \left[O{H}^{-}\right]$

Hence, $pOH=2$

As we know that,

or, $pOH+pH=14$

$pH=14-2=12$