Question

A compound X₂O₃ contains 31.58% oxygen by weight. The atomic mass of X is

(a) 34.66 g mol^-1 

(b) 45.01 g mol^-1

(c) 52.00 g mol^-1

(d) 104.00 g mol^-1

Answer 1

(c) 52.00 g mol^-1

In compound X₂O₃

Percentage of oxygen by weight = 31.58

Percentage of X by weight = 68.42

Let the atomic mass of X = x

\(\frac{2x}{2x+48}\times100=68.42\)

∴ x = 52

So, atomic mass of X is 52g mol^-1.