JEE Main 2020 · 2 September · evening · Single correct · +4 / −1
If you spill a chemical toilet cleaning liquid on your hand, your first aid would be
- (a) aqueous NaOH
- (b) aqueous NaHCO₃
- (c) aqueous NH₃
- (d) vinegar
Answer and solution
Answer (b) aqueous NaHCO₃
Solution
Chemistry ma’am · 3 steps
Toilet cleaners are acidic, so wash the acid off with a mild base that cannot hurt your skin.
- What is spilled. Chemical toilet cleaners contain an acid, usually hydrochloric acid. On the skin, that acid has to be neutralised by a base.
- Pick a gentle base. The base must be mild. A strong base burns the skin just as badly as the acid does.
Option Nature Safe on skin? NaOH strong base no, it is caustic and burns skin NaHCO₃ weak base yes, it neutralises the acid gently NH₃ (aq) base with pungent, irritating fumes no, it irritates skin, eyes and lungs vinegar acid (acetic acid) no, it adds more acid NaHCO₃ + HCl → NaCl + H₂O + CO₂ ↑
- So. Aqueous sodium bicarbonate, option (b), neutralises the acid and leaves only harmless salt, water and carbon dioxide.
The idea to keep. For an acid on the skin use a weak base like NaHCO₃. For an alkali on the skin use a weak acid like dilute acetic acid. Never treat a burn with a strong reagent.
Answer from the NTA final answer key. Solution by PrepWiser.