A certain mass of a gas occupies a volume of $2 \mathrm{dm}^{3}$ at STP. At what temperature the volume of…

A certain mass of a gas occupies a volume of $2 \mathrm{dm}^{3}$ at STP. At what temperature the volume of gas becomes double, keeping the pressure constant?
  1. $540.15^{\circ} \mathrm{C}$
  2. $400.15^{\circ} \mathrm{C}$
  3. $546 \cdot 15^{\circ}$ C
  4. $273.15^{\circ}$ C

Solution

$\begin{array}{l} \mathrm{V}_{1}=2 \mathrm{dm}^{3}, \mathrm{~T}_{1}=273.15 \mathrm{~K} \\ \mathrm{~V}_{2}=4 \mathrm{dm}^{3}, \mathrm{~T}_{2}=? \end{array}$ According to Charle's law, $\begin{array}{l} \frac{V_{1}}{T_{1}}=\frac{V_{2}}{T_{2}} \quad \therefore T_{2}=\frac{V_{2} \times T_{1}}{V_{1}} \\ \therefore T_{2}=\frac{4 \times 273.15}{2}=546.3 \mathrm{~K} \end{array}$ Now, $\mathrm{T} \mathrm{k}=\mathrm{t}^{\circ} \mathrm{C}+273.15$ $\therefore \mathrm{t}^{\circ} \mathrm{C}=\mathrm{T} \mathrm{k}-273.15$ $\therefore \mathrm{t}^{\circ} \mathrm{C}=546.3-273.15=273.15^{\circ} \mathrm{C}$

Asked in: MHT CET 2020 (14 Oct Shift 1)

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