Question

A gaseous oxide contains $30.4$% of nitrogen and one molecule of gas contains two nitrogen atoms. The empirical formula mass of the oxide is _________ g.

• A. $92$
• B. $46$
• C. $108$
• D. none of these

Answer 1

The correct option is B $46$

Nitrogen=$30.4$%

Oxygen=$69.6$%

Determine the chemical formula of the oxide
No.of moles of nitrogen=$\frac{30.4}{14}=2.17$

No.of moles of oxygen=$\frac{69.6}{16}=4.35$

A ratio of moles of nitrogen to oxygen is $2:4=1:2$

Hence the formula of the oxide is ${NO}_2$

Molar mass of the oxide=$14+(2\times 16)=46$

Conclusion: hence the option (B) is correct.