Acid radicals are present in

In qualitative analysis, ions are classified as either acid radicals (anions) or basic radicals (cations).

• Acid radicals are the negative ions (anions) derived from acids. Examples include CO₃^2- (from H₂CO₃), SO₄^2- (from H₂SO₄), NO₃^- (from HNO₃), PO₄^3- (from H₃PO₄), and Cl^- (from HCl).
• Basic radicals are the positive ions (cations) derived from bases. Examples include Na⁺, K⁺, Mg²⁺, Ca²⁺, and Fe²⁺.

The question asks which group contains only acid radicals. Examining each option:

• CO₃^2-, PO₄^3-, Mg²⁺: contains Mg²⁺, which is a basic radical (cation).
• CO₃^2-, SO₄^2-, Na⁺: contains Na⁺, which is a basic radical (cation).
• CO₃^2-, SO₄^2-, NO₃^-: all three are anions derived from acids. This group contains only acid radicals.
• CO₃^2-, SO₄^2-, K⁺: contains K⁺, which is a basic radical (cation).

The correct answer is the group containing CO₃^2-, SO₄^2-, and NO₃^-, as all three are acid radicals.