Question

Calculate the % composition of sodiuam and phosphorous present in monosodium phosphate.

• A. 25.86%, 19.17%
• B. 19.17%, 25.83%
• C. 53.33%, 25.83%
• D. 1.67%, 19.17%

Answer 1

The correct option is B 19.17%, 25.83%

Molecular formula = $Na{H}_{2}P{O}_4$
Molecular mass = $23+(2\times 1)+31+(4\times 16)=120\text{amu}$
% composition of $Na=\left(23/120\right)\times 100=19.17\%$
% composition of $P=\left(31/120\right)\times 100=25.83\%$