1 mole of an ideal gas expands isothermally and reversibly by decreasing pressure form $$210 \mathrm{~kPa}$$ to $$105 \mathrm{~kPa}$$ at $$300 \mathrm{~K}$$. What is the work done? $$\left(\mathrm{R}=8.314 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\right)$$

What is the mass of potassium chloride produced when $$12.25 \mathrm{~g}$$ potassium chlorate undergo decomposition? (At mass: $$\mathrm{K}=39, \mathrm{Cl}=35.5, \mathrm{O}=16$$ )

What type of hybridization is present in $$\mathrm{Ni}$$ of $$\left[\mathrm{Ni}(\mathrm{Cl})_4\right]^{2-}$$ and $$\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}$$ respectively?

What is the molar mass of a metal having density 8.57 g cm$$^{-3}$$ and edge length 3.3 $$\mathop A\limits^o $$ ? (packing efficiency = 68%)