Which from following pairs of compounds is an example of metamerism?

If $$\mathrm{Q}$$ is the heat liberated from the system and $$\mathrm{W}$$ is the work done on the system then first law of thermodynamics can be written as,

Calculate the number of atoms in 5 gram metal that crystallises to form simple cubic unit cell structure having edge length $$336 \mathrm{~pm}$$. (Density of metal $$=9.4 \mathrm{~g} \mathrm{~cm}^{-3}$$ )

Identify the molecule in which central atom undergoes $$\mathrm{sp}^3$$ hybridisation?