Some Basic Concepts of Chemistry - Result Question 31

Subjective Quesions

32. A gaseous mixture contains oxygen and nitrogen in the ratio of $1: 4$ by weight. Therefore, the ratio of their number of molecules is

(1979, 1M)

(a) $1: 4$

(b) $1: 8$

(c) $7: 32$

(d) $3: 16$

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Answer:

Correct Answer: 32. (c)

Solution:

  1. $\frac{\text { Weight of a compound in gram }(w)}{\text { Molar mass }(M)}=$ Number of moles $(n)$

$\begin{aligned} & =\frac{\text { Number of molecules }(N)}{\text { Avogadro number }\left(N_A\right)} \\ \Rightarrow \quad \frac{w\left(\mathrm{O}_2\right)}{32} & =\frac{N\left(\mathrm{O}_2\right)}{N_A} \hspace {10mm}…(i) \end{aligned}$