Question

An oxide of a metal (M) contains $40$% by mass of oxygen. Metal (M) has atomic mass of $24$.The empirical formula of the oxide is :

• A. $M_{2}O$
• B. $MO$
• C. $M_2{O}_3$
• D. $M_3{O}_4$

Answer 1

The correct option is B $MO$

An oxide of a metal (M) contains $40\%$ by mass of oxygen.

100 g of the oxide will contain 60 g of metal and 40 g of oxygen.

Metal (M) has an atomic mass of $24$.

40 g of metal corresponds to $\frac{60}{24}=2.5mol$

Oxygen has an atomic mass of 16.

60 g of oxygen corresponds to $\frac{40}{16}=2.5mol$

Hence, the ratio of the number of moles of metal to oxygen is $1:1$.