What is the number of unpaired electrons in $$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$$ complex?

Which among the following methods is used to prepare Grignard reagent?

Calculate the density of metal having volume of unit cell $$64 \times 10^{-24} \mathrm{~cm}^3$$ and molar mass of metal $$192 \mathrm{~g} \mathrm{~mol}^{-1}$$ containing 4 particles in unit cell.

Calculate the work done when 2 moles of an ideal gas expand from a volume of $$5 \mathrm{~dm}^3$$ to $$7 \times 10^{-3} \mathrm{~m}^3$$ against a constant external pressure of $$2.02 \times 10^5 \mathrm{~Nm}^{-2}$$ ?