Question

Consider the following reactions:

1. Dilute hydrochloric acid reacts with sodium hydroxide.
2. Magnesium oxide reacts with dilute hydrochloric acid.
3. Carbon dioxide reacts with sodium hydroxide.

It is found that in each case:

Options

• Salt and water is formed.

• Neutral salts are formed.

• Hydrogen gas is formed.

• Acidic salts are formed.

Answer 1

Salt and water is formed. 

Explanation: 

1. Neutralization reaction (Acid + Base):

\[\ce{\underset{Hydrochloric acid}{HCl} + \underset{Sodium hydroxide}{NaOH} -> \underset{Sodium chloride}{NaCl} + \underset{Water}{H2O}}\] 

2. Acid-Base Reaction (Metal Oxide + Acid):

\[\ce{\underset{Magnesium oxide}{MgO} + \underset{Hydrochloric acid}{2HCl} -> \underset{Magnesium chloride}{MgCl2} + \underset{Water}{H2O}}\]

3. Reaction of a weak acid (CO₂) with a strong base (NaOH):

If excess NaOH is present, it forms sodium carbonate.

\[\ce{CO2 + 2NaOH -> Na2CO3 + H2O}\]

If NaOH is in limited quantity, it forms sodium bicarbonate.

\[\ce{CO2 + NaOH -> NaHCO3}\]