JEE Previous Year Question

Molar mass of the salt from $\text{NaBr}\text{,}{\text{NaNO}}_3\text{,}\text{KI}$ and ${\text{CaF}}_2$ which does not evolve coloured vapours on heating with concentrated $H_2{\text{SO}}_4$ is _______gmol ${}^{-1}$, (Molar mass in ${\text{gmol}}^{-1}\text{:}\text{Na}\text{:}23\text{,}N\text{:}14\text{,}K\text{:}39$, $O\text{:}16\text{,}\text{Br}\text{:}80\text{,}I\text{:}127\text{,}F\text{:}19\text{,}\text{Ca}\text{:}40$

Topic: JEE PYQ

Answer: 78. Full step-by-step solution below.