The compound used in the treatment of lead poisoning is:

🧠 Match Heavy Metal to Antidote

Chelation therapy is a recall question with four classic pairings:

• Lead ($\mathrm{Pb^{2+}}$) → EDTA (or Ca-EDTA)
• Copper ($\mathrm{Cu^{2+}}$, Wilson's disease) → D-penicillamine
• Iron overload → Desferrioxamine B
• Cancer → Cisplatin

The question asks about lead — answer is EDTA.

🗺️ Pin Down the Choice

(1) Desferrioxamine B — iron chelator, not lead. (2) EDTA — wraps $\mathrm{Pb^{2+}}$ in a stable hexadentate cage that the kidneys excrete. ✓ (3) Cisplatin — antitumour drug. (4) D-penicillamine — copper chelator.

⚡ The "Six-Arm Hug" Image

EDTA's six donor atoms wrap around $\mathrm{Pb^{2+}}$ like a tight hug, locking it into a water-soluble complex that flushes out via urine. That mental image fixes the lead → EDTA pairing for life.

⚠️ Free EDTA Is Dangerous

Clinical detail (often tested at higher levels): pure $\mathrm{Na_2EDTA}$ would also chelate $\mathrm{Ca^{2+}}$ and cause fatal hypocalcaemia. The form actually administered for lead poisoning is calcium-disodium EDTA ($\mathrm{CaNa_2EDTA}$) — it swaps Ca for Pb in the body. Plain EDTA is the correct textbook answer, but the calcium-buffered form is what reaches the patient.

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