The total number of molecular orbitals formed from $$2 \mathrm{s}$$ and $$2 \mathrm{p}$$ atomic orbitals of a diatomic molecule is __________.

The mass of sodium acetate $$\left(\mathrm{CH}_3 \mathrm{COONa}\right)$$ required to prepare $$250 \mathrm{~mL}$$ of $$0.35 \mathrm{~M}$$ aqueous solution is ________ g. (Molar mass of $$\mathrm{CH}_3 \mathrm{COONa}$$ is $$82.02 \mathrm{~g} \mathrm{~mol}^{-1}$$)

$$0.05 \mathrm{~cm}$$ thick coating of silver is deposited on a plate of $$0.05 \mathrm{~m}^2$$ area. The number of silver atoms deposited on plate are ________ $$\times 10^{23}$$. (At mass $$\mathrm{Ag}=108, \mathrm{~d}=7.9 \mathrm{~g} \mathrm{~cm}^{-3}$$)

The compound formed by the reaction of ethanal with semicarbazide contains _________ number of nitrogen atoms.