Question

Which of the following phenomena occur, when a small amount of acid is added to water? (i) Ionisation (ii) Neutralisation (iii) Dilution (iv) Salt formation.

• A. (i) and (ii)
• B. (i) and (iii)
• C. (ii) and (iii)
• D. (ii) and (iv)

Answer 1

The correct option is B

(i) and (iii)

Explanation for the correct answer:-

Option (B) (i) and (iii)

• When an acid is added to water, the acid dissociates into constituent ions.
• This results in the dilution of the acid.
• A dilute acid is also called an aqueous solution in which the acid releases hydronium ions $\left({\mathrm{H}}^{+}\right)$ and thus undergoes ionisation.
• If we take Hydrochloric acid and add it to water it dissociates into its constituent ions:

$\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{H}}^{+}\left(\mathrm{aq}\right)+{\mathrm{Cl}}^{-}\left(\mathrm{aq}\right)$

• Hence it is the correct option.

Explanation for the incorrect option:-

Option (A) (i) and (ii)

• Neutralisation reaction is a reaction where an acid and a base react and the product formed is salt and water.
• Addition of acid in water is not a neutralization reaction.
• Hence it is the incorrect option.

Option (C) (ii) and (iii)

• Neutralisation reaction is a reaction where an acid and a base react and the product formed is salt and water.
• Addition of acid in water is not a neutralization reaction.
• Hence it is the incorrect option.

Option (D) (ii) and (iv)

• Salt formation occurs when acid and base react and this type of reaction is called a neutralization reaction.
• Addition of acid in water is not a neutralization reaction.
• Hence it is the incorrect option.

Therefore, option (B) is the correct answer.