Q7 / 160 · TS EAMCET 2020 (14 Sep Shift 2) · Chemistry

What is the ratio of kinetic energy of 7 grams of nitrogen and 4 grams of oxygen at $T(\mathrm{~K})$ ?

  • A
    1 : 2
  • Correct answer
    B
    2 : 1
  • C
    3 : 1
  • D
    4 : 1

Solution

The expression of average kinetic energy of a gas molecule is, $\mathrm{KE}=\frac{3}{2} \times n R T$ When, temperature ( $T$ in $\mathrm{K}$ ) is constant, $\mathrm{KE} \propto n$ (mole) $\Rightarrow \frac{(\mathrm{KE})_{\mathrm{N}_2}}{(\mathrm{KE})_{\mathrm{O}_2}}=\frac{n_{\mathrm{N}_2}}{n_{\mathrm{O}_2}}=\frac{7 / 28}{4 / 32}=\frac{1}{4} \times \frac{8}{1}=2: 1$

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

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