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%)

The wavelength of blue light is $$480 \mathrm{~nm}$$. What is frequency of this light?

Identify the reagent used in following conversion. Chloroethane $$\stackrel{\mathrm{A}}{\longrightarrow}$$ Nitro ethane