Which of the following is correctly identified?
Ca(OH)2, weak base
H2CO3, strong acid
NaOH, strong base
HCl, weak acid
NH3, strong acid
The Correct Answer and Explanation is :
The correct identification in the list is NaOH, strong base.
Here’s an explanation for each compound:
- Ca(OH)2, weak base – Incorrect: Calcium hydroxide (Ca(OH)2) is a strong base, not a weak base. It dissociates completely in water to release hydroxide ions (OH⁻), making the solution strongly alkaline. Although it’s not as soluble as other strong bases (like sodium hydroxide), its dissociation in water is significant enough to classify it as a strong base.
- H2CO3, strong acid – Incorrect: Carbonic acid (H2CO3) is a weak acid. It partially dissociates in water to release hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻). Since it doesn’t dissociate completely, it is classified as a weak acid, not a strong acid like hydrochloric acid (HCl).
- NaOH, strong base – Correct: Sodium hydroxide (NaOH) is a strong base. It dissociates completely in water to release sodium ions (Na⁺) and hydroxide ions (OH⁻), making the solution highly alkaline. Strong bases, like NaOH, have high dissociation in water, resulting in a large concentration of OH⁻ ions.
- HCl, weak acid – Incorrect: Hydrochloric acid (HCl) is a strong acid. It dissociates completely in water, releasing hydrogen ions (H⁺) and chloride ions (Cl⁻). Strong acids, such as HCl, fully ionize in aqueous solution, making them highly effective at increasing the concentration of H⁺ ions in solution.
- NH3, strong acid – Incorrect: Ammonia (NH3) is not an acid; it is a weak base. When ammonia dissolves in water, it accepts a proton (H⁺) to form ammonium ions (NH₄⁺) and hydroxide ions (OH⁻), making the solution basic. Therefore, it is classified as a weak base, not a strong acid.
In summary, the only correct identification is NaOH as a strong base, while the others are either incorrectly identified or misclassified.