$ \Rightarrow \frac{{{T_2}}}{{{T_1}}} = {\left( {\frac{1}{8}} \right)^{\frac{{1.5 - 1}}{{1.5}}}} = {\left( {\frac{1}{8}} \right)^{\frac{1}{3}}} = \frac{1}{2}$
$ \Rightarrow {T_2} = \frac{{{T_1}}}{2} = \frac{{300}}{2} = 150K$.
Assertion $A$ : If $dQ$ and $dW$ represent the heat supplied to the system and the work done on the system respectively. Then according to the first law of thermodynamics $d Q=d U-d W$.
Reason $R :$ First law of thermodynamics is based on law of conservation of energy.
In the light of the above statements, choose the correct answer from the option given below :

