Which ion is responsible for the acidic nature of hydrochloric acid?

Distinguish between the following pair of compounds using the reagent given in the bracket.

Dilute hydrochloric acid and dilute sulphuric acid. (using lead nitrate solution)

Choose the method of preparation of Lead chloride, from the methods given in the list:

[List: A. Neutralization B.Precipitation C.Direct combination D.Substitution]

Identify the gas evolved $\left(\mathrm{Y}\right)$ in the following equation:

$\underset{\mathrm{Sodium} \mathrm{sulphite}}{{\mathrm{Na}}_2{\mathrm{SO}}_3}+\underset{\mathrm{Hydrochloric} \mathrm{acid}}{\mathrm{HCl}}\to \underset{\mathrm{Sodium} \mathrm{chloride}}{\mathrm{NaCl}}+\mathrm{Y}\underset{}{\uparrow }+{\mathrm{H}}_2\mathrm{O}$

Identify the type of reaction given below:

$\underset{\mathrm{Iron} \left(\mathrm{II}\right) \mathrm{sulphide}}{\mathrm{FeS}}+\underset{\mathrm{Hydrochloric} \mathrm{acid}}{2\mathrm{HCl}}\to \underset{\mathrm{Ferrous} \mathrm{chloride}}{{\mathrm{FeCl}}_2}+\underset{\mathrm{Hydrogen} \mathrm{sulphide}}{{\mathrm{H}}_2\mathrm{S}\uparrow }$