(a) For the reaction

$$2 \mathrm{~N}_2 \mathrm{O}_{5(\mathrm{~g})} \rightarrow 4 \mathrm{NO}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})} \text { at } 318 \mathrm{~K}$$

Calculate the rate of reaction if rate of disappearance of $$\mathrm{N}_2 \mathrm{O}_{5(\mathrm{~g})}$$ is $$1.4 \times 10^{-3} \mathrm{~m} \mathrm{~s}^{-1}$$.

(b) For a first order reaction derive the relationship $$\mathbf{t}_{99 \%}=\mathbf{2} \mathbf{t}_{90 \%}$$

(a) On the basic of crystal field theory write the electronic configuration for $$\mathrm{d}^5$$ ion with a strong field ligand for which $$\Delta_0>\mathrm{P}$$.

(b) $$\left[\mathrm{Ni}(\mathrm{CO})_4\right]$$ has tetrahedral geometry while $$\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}$$ has square planar yet both exhibit diamagnetism. Explain.

[Atomic number : $$\mathrm{Ni}=28$$ ]

(a) Illustrate Sandmeyer's reaction with an equation.

(b) Explain, why $$\left(\mathrm{CH}_3\right)_2 \mathrm{NH}$$ is more basic than $$\left(\mathrm{CH}_3\right)_3 \mathrm{~N}$$ in aqueous solution.

Give reasons for any 3 of the following observations:

(a) Penta-acetate of glucose does not react with hydroxylamine.

(b) Amino acids behave like salts.

(c) Water soluble vitamins must be taken regularly in diet.

(d) The two strands in DNA are complimentary to each other.