MCQ
Which metal is protected by a layer of its own oxide
- ✓$Al$
- B$Ag$
- C$Au$
- D$Fe$
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$MgO + 2HCl \longrightarrow MgCl_2 + H_2O$
| Cations | Group reaction |
| $P \rightarrow Pb ^{2+}, Cu ^{2+}$ | $(i)$ $H _2 S$ gas in presence of dilute $HCl$ |
| $Q \rightarrow Al ^{3+}, Fe ^{3+}$ | $(ii)$ $\left( NH _4\right)_2 CO _3$ in presence of $NH _4 OH$ |
| $R \rightarrow Co ^{2+}, Ni ^{2+}$ | $(iii)$ $NH _4 OH$ in presence of $NH _4 CI$ |
| $S \rightarrow Ba ^{2+}, Ca ^{2+}$ | $(iv)$ $H _2 S$ in presence of $NH _4 OH$ |