Molar mass of the salt from NaBr, \(NaNO_3\), KI and \(CaF_2\) which does not evolve coloured vapours on heating with concentrated \(H_2SO_4\) is _____ g \(mol^{−1}\). (Molar mass in g mol−1: Na : 23, N : 14, K : 39, O : 16, Br : 80, I : 127, F : 19, Ca : 40)