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Activity 2.4 — Base + Metal → Salt + H₂
NCERT Activity 2.4: Add zinc granules to NaOH solution and warm gently. H₂ gas evolves — proving that strong bases can also release H₂ with AMPHOTERIC metals (Zn, Al, Pb, Sn).
How To Perform
1
Add NaOH Solution
Take ~5 mL of NaOH in a test tube (caustic — handle with care).
2
Add Zinc Granules
Drop in a few Zn granules. Nothing happens at room temperature.
3
Heat Gently
Warm the tube. Brisk effervescence of H₂ starts on the zinc.
4
Pop Test
Burning matchstick at mouth → 'POP' confirms H₂.
5
Conclude
Zn is amphoteric — most metals don't react with bases.
⚠️ Safety Notes
- •NaOH is CAUSTIC — wear goggles, avoid skin contact.
- •Heat GENTLY — strong heating can cause bumping and splattering of caustic NaOH.
- •Keep the tube mouth away from your face during the pop test.