Question

Calculate the ratio of atomic masses of Phosphorous and Oxygen in $P_2{O}_5$.

• A. 30 : 31
• B. 31 : 40
• C. 37 : 40
• D. 33 : 34

Answer 1

The correct option is B 31 : 40

The atomic mass of Phosphorous = 31 u

The atomic mass of Oxygen = 16 u
Atomic masses of Phosphorous in $P_2{O}_5$ = 2 x 31 = 62 u
Atomic masses of Oxygen in $P_2{O}_5$ = 16 x 5 = 80 u
Ratio = 62 : 80 = 31 : 40