Question

The number of molecules in $100\, mL$ of $0.02\,NH_2SO_4$ is

• A. $ 6.022\times 10^{22}$
• B. $ 6.02\times 10^{21}$
• C. $ 6.02\times 10^{20}$
• D. $ 6.02\times 10^{18}$

Answer 1

Answer: (C)

For $H _{2} SO _{4}$,
Normality, $N=2\, M$
or $M=\frac{N}{2}=\frac{0.02}{2}=0.01$
Moles of $H _{2} SO _{4}=\frac{0.01 \times 100}{1000}$
$=1 \times 10^{-3}$
$\therefore $ Number of molecules in $100\, mL$ of $0.02\, N$
$H _{2} SO _{4} =1 \times 10^{-3} \times N_{A}$
$=1 \times 10^{-3} \times 6.023 \times 10^{23}$
$=6.023 \times 10^{20}$