Which of the following statements is incorrect?

Question

Accepted Answer

1. **Option A is correct:** Sodium hydrogen carbonate ($NaHCO_3$) thermally decomposes to give sodium carbonate ($Na_2CO_3$), water, and carbon dioxide.
2. **Option B is correct:** Alkali metals like sodium dissolve in liquid ammonia to give deep blue solutions which are conducting in nature due to ammoniated electrons.
3. **Option C is correct:** Sodium hydroxide ($NaOH$) reacts with silica ($SiO_2$), a major component of glass, to form sodium silicate ($Na_2SiO_3$). This causes etching of glass.
4. **Option D is incorrect:** Aluminium is an amphoteric metal. It reacts with excess aqueous sodium hydroxide to form a soluble complex, sodium tetrahydroxidoaluminate(III) (or sodium aluminate), and liberates hydrogen gas. The reaction is:
 $$2Al(s) + 2NaOH(aq) + 6H_2O(l) \rightarrow 2Na^+[Al(OH)_4]^-(aq) + 3H_2(g)$$ 
 It does not form insoluble aluminium hydroxide ($Al(OH)_3$) in excess alkali.

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