Question

The % compositions of sodium and phosphorous present in monosodium phosphate are respectively:

• A. $19.17\%,25.83\%$
• B. $23.18\%,25.83\%$
• C. $19.17\%,53.33\%$
• D. $23.18\%,53.33\%$

Answer 1

The correct option is A $19.17\%,25.83\%$

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 $P=\left(31/120\right)\times 100=25.83\%$