Read the passage carefully and answer the questions that follow :

Nucleophilic Substitution Nucleophilic Substitution reaction of haloalkane can be conducted according to both $$\mathrm{S}_{\mathrm{N}} 1$$ and $$\mathrm{S}_{\mathrm{N}} 2$$ mechanisms. $$S_N 1$$ is a two step reaction while $$S_N 2$$ is a single step reaction. For any haloalkane which mechanism is followed depends on factors such as structure of haloalkane, properties of leaving group, nucleophilic reagent and solvent.

Influences of solvent polarity: In $$\mathrm{S}_{\mathrm{N}} 1$$ reaction, the polarity of the system increases from the reactant to the transition state, because a polar solvent has a greater effect on the transition state than the reactant, thereby reducing activation energy and accelerating the reaction. In $$\mathrm{S}_{\mathrm{N}} 2$$ reaction, the polarity of the system generally does not change from the reactant to the transition state and only charge dispersion occurs. At this time, polar solvent has a great stabilizing effect on $$\mathrm{Nu}$$ than the transition state, thereby increasing activation energy and slow down the reaction rate. For example, the decomposition rate $$\left(\mathrm{S}_{\mathrm{N}} 1\right)$$ of tertiary chlorobutane at $$25^{\circ} \mathrm{C}$$ in water (dielectric constant 79) is 300000 times faster than in ethanol (dielectric constant 24 ). The reaction rate $$\left(\mathrm{S}_{\mathrm{N}} 2\right)$$ of 2 -Bromopropane and $$\mathrm{NaOH}$$ in ethanol containing $$40 \%$$ water is twice slower than in absolute ethanol. Hence the level of solvent polarity has influence on both $$\mathrm{S}_{\mathrm{N}} 1$$ and $$\mathrm{S}_{\mathrm{N}} 2$$ reaction, but with different results. Generally speaking weak polar solvent is favourable for $$\mathrm{S}_{\mathrm{N}} 2$$ reaction, while strong polar solvent is favourable for $$\mathrm{S}_{\mathrm{N}} 1$$. Generally speaking the substitution reaction of tertiary haloalkane is based on $$S_N 1$$ mechanism in solvents with a strong polarity (for example ethanol containing water).

Answer the following questions :

(a) Why racemisation occurs in $$S_N 1$$ ?

(b) Why is ethanol less polar than water?

(c) Which one of the following in each pair is more reactive towards $$S_N 2$$ reaction?

(i) $$\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{I} \text { or } \mathrm{CH}_3 \mathrm{CH}_2-\mathrm{Cl}$$

(ii)

OR

(c) Arrange the following in the increasing order of their reactivity towards $$S_N 1$$ reactions:

(i) 2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane

(ii) 1-Bromo-3-methylbutane, 2-Bromo-2methylbutane, 2-Bromo-3-methylbutane