(c) At constant volume $P \propto T \Rightarrow \frac{P_{1}}{P_{2}} = \frac{T_{1}}{T_{2}} \Rightarrow \frac{P_{1}}{P_{2}} = \frac{300}{400} = \frac{3}{4}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.