(b) $\chi \propto \frac{1}{T}$ $\therefore\chi_{1}T_{1} = \chi_{2}T_{2}$ Hence $T_{2} = \frac{1.2 \times 10^{- 5} \times 300}{1.8 \times 10^{- 5}} = 200\ K$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.