Molar mass of the salt from $$\mathrm{NaBr}, \mathrm{NaNO}_3, \mathrm{KI}$$ and $$\mathrm{CaF}_2$$ which does not evolve coloured vapours on heating with concentrated $$\mathrm{H}_2 \mathrm{SO}_4$$ is ________ $$\mathrm{g} \mathrm{~mol}{ }^{-1}$$.

(Molar mass in $$\mathrm{g} \mathrm{~mol}^{-1}: \mathrm{Na}: 23, \mathrm{~N}: 14, \mathrm{~K}: 39, \mathrm{O}: 16, \mathrm{Br}: 80, \mathrm{I}: 127, \mathrm{~F}: 19, \mathrm{Ca}: 40)$$

The total number of hydrogen atoms in product A and product B is _________.

The number of species from the following in which the central atom uses $$\mathrm{sp}^3$$ hybrid orbitals in its bonding is __________.

$$\mathrm{NH}_3, \mathrm{SO}_2, \mathrm{SiO}_2, \mathrm{BeCl}_2, \mathrm{CO}_2, \mathrm{H}_2 \mathrm{O}, \mathrm{CH}_4, \mathrm{BF}_3$$

$$\lim _\limits{x \rightarrow 0} \frac{e^{2|\sin x|}-2|\sin x|-1}{x^2}$$