What is $$\mathrm{pH}$$ of solution containing $$50 \mathrm{~mL}$$ each of $$0.1 \mathrm{~M}$$ sodium acetate and $$0.01 \mathrm{~M}$$ acetic acid? $$\left(\mathrm{pK}_{\mathrm{a}} \mathrm{CH}_3 \mathrm{COOH}=4.50\right)$$

Calculate amount of methane formed by liberation of $$149.6 \mathrm{~kJ}$$ of heat using following equation.

$$\mathrm{C}_{(\mathrm{s})}+2 \mathrm{H}_{2(\mathrm{~g})} \longrightarrow \mathrm{CH}_{4(\mathrm{~g})} \quad \Delta \mathrm{H}=-74.8 \mathrm{~kJ} / \mathrm{mol}$$

Which from following polymers is used to obtain tyre cords?

Electrolytic cells containing $$\mathrm{Zn}$$ and $$\mathrm{Al}$$ salt solutions are connected in series. If $$6.5 \mathrm{~g}$$ of $$\mathrm{Zn}$$ is deposited in one cell calculate mass of $$\mathrm{Al}$$ deposited in second cell (molar mass : $$\mathrm{Zn}=65, \mathrm{Al}=27$$ ) by passing definite quantity of electricity?