JEE MAIN - Chemistry (2023 - 25th January Evening Shift - No. 21)
Number of hydrogen atoms per molecule of a hydrocarbon A having 85.8% carbon is __________
(Given : Molar mass of A = 84 g mol$$^{-1}$$)
(Given : Molar mass of A = 84 g mol$$^{-1}$$)
Answer
12
Explanation
Molar mass of a hydrocarbon $(A)=84 \mathrm{~g} / \mathrm{mol}$
Mass of carbon in $1 \mathrm{~mol}$ of $(A)=\frac{85.8}{100} \times 84$
$$ =72 ~\mathrm{gm} $$
Mass of hydrogen in $1 \mathrm{~mol}$ of $(A)=12 ~\mathrm{gm}$
$\therefore$ Number of $\mathrm{H}$-atoms in a molecule of $(\mathrm{A})=12$.
Mass of carbon in $1 \mathrm{~mol}$ of $(A)=\frac{85.8}{100} \times 84$
$$ =72 ~\mathrm{gm} $$
Mass of hydrogen in $1 \mathrm{~mol}$ of $(A)=12 ~\mathrm{gm}$
$\therefore$ Number of $\mathrm{H}$-atoms in a molecule of $(\mathrm{A})=12$.
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