It is desired to reduce the volume of 1000 cm of a gas by `25%`. To what temperature the gas be cooled if the initial temperature is `125^@C` and the pressure remains constant ?

Explanation

The desired increase in the volume of gas is
`20%` of `80 cm^(3)=(80)/(100)xx20=16 cm^(3)`
Thus, the final volume of the gas is `80+16=96 cm^(3)`.
Now, `V_(1)=80 cm^(3)`, `V_(2)=96 cm^(3)`
`T_(1)=25^(@)C=298 K`, `T_(2)=?`
Applying Charles'law, we get
`(V_(1))/(T_(1))=(V_(2))/(T_(2))`
`:. T_(2)=(V_(2)T_(1))/(V_(1))=(96cm^(3)xx298 K)/(80 cm^(3))=357.6 K`
`=375.6-273=84.6^(@)C`