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Among the four statements below about chemical reactions involving p-block and other inorganic compounds, identify the ONE that is INCORRECT: (P) The stability of dihalides follows the order: SiX2 < GeX2 < SnX2 < PbX2 (Q) The reaction 2NH3 + H2O + CO2 -> (NH4)2CO3 correctly represents ammonia absorbing carbon dioxide in water (R) When Na2CO3*10H2O is heated at a temperature below 373 K, it decomposes into Na2O, CO2, and 10H2O (S) Boric acid forms a polymeric network because of intermolecular hydrogen bonding

1. (P) The stability of dihalides follows the order: SiX2 < GeX2 < SnX2 < PbX2
2. (Q) The reaction 2NH3 + H2O + CO2 -> (NH4)2CO3 correctly represents ammonia absorbing carbon dioxide in water
3. (R) When Na2CO3*10H2O is heated below 373 K, it decomposes into Na2O, CO2, and 10H2O
4. (S) Boric acid forms a polymeric network because of intermolecular hydrogen bonding

Correct answer: (R) When Na2CO3*10H2O is heated below 373 K, it decomposes into Na2O, CO2, and 10H2O

Solution

Heating Na2CO3*10H2O below 373 K causes it to lose water of crystallisation (efflorescence), giving anhydrous Na2CO3 (or monohydrate), NOT Na2O and CO2; decomposition into Na2O requires very high temperatures. Statement R is therefore incorrect.

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