Vapor pressure in mm of mercury of solid and liquid ammonia is given by

​$$I_nP = 23.1 – (3749/T) \space{ and }\space I_nP = 19.6 –(3049/T),$$ find out the triple point.

Correct option is C

​$$\begin{aligned}&\text{We are given two equations for vapor pressure of solid and liquid ammonia in terms of temperature } T, \\&\text{and asked to find the triple point, i.e., where both phases coexist:} \\&\ln P_{\text{solid}} = \ln P_{\text{liquid}} \\[1.5em]&\textbf{Write given equations} \\&\ln P_{\text{solid}} = 23.1 - \frac{3749}{T} \\&\ln P_{\text{liquid}} = 19.6 - \frac{3049}{T} \\[1.5em]&\textbf{Equating the two} \\&23.1 - \frac{3749}{T} = 19.6 - \frac{3049}{T} \\[1.5em]&\textbf{Solve} \\&\text{Subtract:} \\&23.1 - 19.6 = \frac{3749 - 3049}{T} \Rightarrow 3.5 = \frac{700}{T} \Rightarrow T = \frac{700}{3.5} = \boxed{200\, \text{K}}\end{aligned}$$​​