Number of hydrogen atoms per molecule of a hydrocarbon A having 85.8% carbon is __________
(Given : Molar mass of A = 84 g mol$^{-1}$)
Answer (integer)
12
Solution
Molar mass of a hydrocarbon $(A)=84 \mathrm{~g} / \mathrm{mol}$
<br/><br/>
Mass of carbon in $1 \mathrm{~mol}$ of $(A)=\frac{85.8}{100} \times 84$
<br/><br/>
$=72 ~\mathrm{gm}$
<br/><br/>
Mass of hydrogen in $1 \mathrm{~mol}$ of $(A)=12 ~\mathrm{gm}$
<br/><br/>
$\therefore$ Number of $\mathrm{H}$-atoms in a molecule of $(\mathrm{A})=12$.
About this question
Subject: Chemistry · Chapter: Some Basic Concepts of Chemistry · Topic: Mole Concept
This question is part of PrepWiser's free JEE Main question bank. 163 more solved questions on Some Basic Concepts of Chemistry are available — start with the harder ones if your accuracy is >70%.