The number of ions from the following that are expected to behave as oxidising agent is: Sn4+,\ Sn2+,\ Pb2+,\ Tl3+,\…

Strategy: Identify which ions from the list behave as oxidising agents (can be reduced; higher OS is unstable and prefers to gain electrons).

Step 1: Ion Analysis Given: $\ce{Sn^{4+}, Sn^{2+}, Pb^{2+}, Tl^{3+}, Pb^{4+}, Tl^+}$

An ion acts as an oxidising agent if its higher oxidation state is unstable compared to the lower state (inert pair effect → higher OS less stable in heavier elements):

• $\ce{Sn^{4+}}$: Sn(IV) is stable (Sn exists readily as +4). Not a strong oxidising agent. ❌
• $\ce{Sn^{2+}}$: Can be oxidised (reducing agent), not an oxidising agent. ❌
• $\ce{Pb^{2+}}$: Pb(II) is the stable state. Not an oxidising agent. ❌
• $\ce{Tl^{3+}}$: Tl(I) is much more stable (inert pair effect). Tl³⁺ readily gains 2e⁻ to become Tl⁺ → strong oxidising agent ✅
• $\ce{Pb^{4+}}$: Pb(II) is more stable. Pb⁴⁺ readily gains 2e⁻ to become Pb²⁺ → strong oxidising agent ✅
• $\ce{Tl^+}$: Tl(I) is the stable state; not an oxidising agent. ❌

Step 2: Count Oxidising agents: $\ce{Tl^{3+}}$ and $\ce{Pb^{4+}}$ → 2 ions

$\boxed{\text{Answer: (B) 2}}$