Answer:
1658.01807 cm³
Explanation:
[tex]V_1[/tex] = Initial volume = 640 cm³
[tex]V_2[/tex] = Final volume
[tex]T_1[/tex] = Initial temperature = 20°C
[tex]T_2[/tex] = Final temperature = -20°C
[tex]P_1[/tex] = Initial pressure = 1 atm (sea level)
Final pressure
[tex]P_2=\dfrac{1}{3}P_1\\\Rightarrow P_2=\dfrac{1}{3}\ atm[/tex]
We have the relation
[tex]\dfrac{P_1V_1}{T_1}=\dfrac{P_2V_2}{T_2}\\\Rightarrow V_2=\dfrac{P_1V_1T_2}{T_1P_2}\\\Rightarrow V_2=\dfrac{1\times 640\times 253.15}{293.15\times \dfrac{1}{3}}\\\Rightarrow V_2=1658.01807\ cm^3[/tex]
The final volume is 1658.01807 cm³