The valency of lead is/are

Both A and B

Lead (Pb), a heavy metal and a post-transition element, exhibits two common valencies: +2 and +4.

Explanation:

• Electronic Configuration of Lead: The atomic number of lead is 82, and its electronic configuration is: [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p². The outermost shell contains two electrons in the 6s orbital and two in the 6p orbital, which determine its valency.
• Variable Valency: Lead exhibits variable valency due to the inert pair effect.
  • +2 Valency: Lead loses the two 6p electrons, resulting in a +2 oxidation state. This is more stable due to the inert pair effect. Example: PbCl₂ (Lead(II) chloride).
  • +4 Valency: Lead loses all four valence electrons (2 from 6s and 2 from 6p), resulting in a +4 oxidation state. Example: PbO₂ (Lead(IV) oxide).
• Inert Pair Effect: The tendency of the 6s electrons to remain non-bonding (inert) makes the +2 oxidation state more stable than +4 in most cases.
• Applications and Stability: Lead compounds in the +2 state (like PbCl₂) are more stable and common, while the +4 state (like PbO₂) is less stable and acts as a strong oxidizing agent.

The valency of lead is 2 and 4, with +2 being more stable due to the inert pair effect. 
Correct Option: D