What volume of $$0.2 \mathrm{~M}$$ Acetic acid is to be added to $$100 \mathrm{ml}$$ of $$0.4 \mathrm{M}$$ Sodium acetate so that a Buffer solution of $$\mathrm{pH}$$ equal to 4.94 is obtained? $$(\mathrm{pK}_{\mathrm{a}}$$ of $$\mathrm{CH}_3 \mathrm{COOH}=4.76)$$
Arrange the compounds $$\mathrm{A}, \mathrm{B}, \mathrm{C}$$ and $$\mathrm{D}$$ in the increasing order of their reactivity towards $$\mathrm{S_N}1$$ reaction.
$$ \begin{aligned} & \mathrm{A}=\mathrm{C}_6 \mathrm{H}_5 \mathrm{CH}_2 \mathrm{Cl} \\ & \mathrm{B}=\mathrm{C}_6 \mathrm{H}_5 \mathrm{Cl} \\ & \mathrm{C}=\mathrm{CH}_2=\mathrm{CH}-\mathrm{Cl} \\ & \mathrm{D}=\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{Cl} \end{aligned}$$
For a reaction $$5 X+Y \rightarrow 3 Z$$, the rate of formation of $$Z$$ is $$2.4 \times 10^{-5} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$$ Calculate the average rate of disappearance of $$\mathrm{X}$$.
In the redox reaction between $$\mathrm{Cr}_2 \mathrm{O}_7^{2-} / \mathrm{H}^{+}$$ and sulphite ion, what is the number of moles of electrons involved in producing 3.0 moles of the oxidised product?