Q8 / 160 · TS EAMCET 2022 (19 Jul Shift 1) · Chemistry

The average molecular weight of the air which has $21 \%$ of $\mathrm{O}_2$ and $79 \%$ of $\mathrm{N}_2$, is

  • A
    44.8
  • B
    100
  • C
    14.4
  • Correct answer
    D
    28.8

Solution

Average molecular weight $=21 \%$ of $\mathrm{O}_2+79 \%$ of $\mathrm{N}_2$ $$ \begin{aligned} & \Rightarrow \quad \frac{21}{100} \times 32+\frac{79}{100} \times 28 \\ & \Rightarrow \quad 6.72+22.12=28.8 \end{aligned} $$

Hence, the correct answer is option: 'D'.

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