Assertion A : During the boiling of water having temporary hardness, Mg(HCO₃)₂ is converted to MgCO₃.
Reason R : The solubility product of Mg(OH)₂ is greater than that of MgCO₃.

Question

Match List - I with List - II :

Choose the correct answer from the options given below :

Answer 1

To address the assertion and reason provided, let's examine both statements in detail:

Assertion (A): "During the boiling of water having temporary hardness, Mg(HCO₃)₂ is converted to MgCO₃."
- The temporary hardness of water is generally caused by the presence of bicarbonate salts such as calcium bicarbonate [\text{Ca(HCO}_3\text{)}_2] and magnesium bicarbonate [\text{Mg(HCO}_3\text{)}_2].
- When water containing these bicarbonates is boiled, the bicarbonates decompose. Specifically, magnesium bicarbonate decomposes to form magnesium hydroxide [\text{Mg(OH)}_2], not magnesium carbonate [\text{MgCO}_3]:
- 2\ \text{Mg(HCO}_3\text{)}_2 \rightarrow 2\ \text{MgCO}_3 + 2\ \text{CO}_2 + 2\ \text{H}_2\text{O} \rightarrow \text{Mg(OH)}_2 + 2\ \text{CO}_2.
- Therefore, the assertion is incorrect as it mistakenly states that Mg(HCO₃)₂ is converted directly to MgCO₃, which is not the case.
Reason (R): "The solubility product of Mg(OH)₂ is greater than that of MgCO₃."
- The solubility product (Ksp) is a constant for a given solid at a particular temperature. It represents the extent to which a compound can dissolve in water.
- The solubility product of Mg(OH)₂ is indeed greater compared to that of MgCO₃, which means Mg(OH)₂ is less soluble than MgCO₃ in water.
- This statement is true based on the general solubility order of these compounds.

Based on the evaluation above:

Assertion (A) is false because it incorrectly identifies the conversion product of Mg(HCO₃)₂ upon boiling.
Reason (R) is true; it correctly states the relative solubility products of Mg(OH)₂ and MgCO₃.
Thus, the correct option is: A is false but R is true.

Answer 2

To address the assertion and reason provided, let's examine both statements in detail:

Assertion (A): "During the boiling of water having temporary hardness, Mg(HCO₃)₂ is converted to MgCO₃."
- The temporary hardness of water is generally caused by the presence of bicarbonate salts such as calcium bicarbonate [\text{Ca(HCO}_3\text{)}_2] and magnesium bicarbonate [\text{Mg(HCO}_3\text{)}_2].
- When water containing these bicarbonates is boiled, the bicarbonates decompose. Specifically, magnesium bicarbonate decomposes to form magnesium hydroxide [\text{Mg(OH)}_2], not magnesium carbonate [\text{MgCO}_3]:
- 2\ \text{Mg(HCO}_3\text{)}_2 \rightarrow 2\ \text{MgCO}_3 + 2\ \text{CO}_2 + 2\ \text{H}_2\text{O} \rightarrow \text{Mg(OH)}_2 + 2\ \text{CO}_2.
- Therefore, the assertion is incorrect as it mistakenly states that Mg(HCO₃)₂ is converted directly to MgCO₃, which is not the case.
Reason (R): "The solubility product of Mg(OH)₂ is greater than that of MgCO₃."
- The solubility product (Ksp) is a constant for a given solid at a particular temperature. It represents the extent to which a compound can dissolve in water.
- The solubility product of Mg(OH)₂ is indeed greater compared to that of MgCO₃, which means Mg(OH)₂ is less soluble than MgCO₃ in water.
- This statement is true based on the general solubility order of these compounds.

Based on the evaluation above:

Assertion (A) is false because it incorrectly identifies the conversion product of Mg(HCO₃)₂ upon boiling.
Reason (R) is true; it correctly states the relative solubility products of Mg(OH)₂ and MgCO₃.
Thus, the correct option is: A is false but R is true.

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