(d) $PV = NkT \Rightarrow \frac{N_{A}}{N_{B}} = \frac{P_{A}V_{A}}{P_{B}V_{B}} \times \frac{T_{B}}{T_{A}}$ $\Rightarrow \frac{N_{A}}{N_{B}} = \frac{P \times V \times (2T)}{2P \times \frac{V}{4} \times T} = \frac{4}{1}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.