Question

Consider the following two reactions A and B:

The numerical value of [molar mass of $x$ + molar mass of $y$] is ___. 
 

• A. $46$
• B. $88$
• C. $160$
• D. $4$
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Hint:

Acids react with sodium to give $\mathrm{H_2}$, while carboxylic acids react with bicarbonates to release $\mathrm{CO_2}$.

Answer 1

The Correct Option is A

Step 1: Identifying gas $(x)$ in reaction (A).
Phenol reacts with sodium as:
\[ 2\mathrm{C_6H_5OH} + 2\mathrm{Na} \rightarrow 2\mathrm{C_6H_5ONa} + \mathrm{H_2}(x) \] Thus, gas $(x)$ is hydrogen.
Molar mass of $\mathrm{H_2} = 2\,\text{g mol}^{-1}$.
Step 2: Identifying gas $(y)$ in reaction (B).
Benzoic acid reacts with sodium bicarbonate as:
\[ \mathrm{C_6H_5COOH} + \mathrm{NaHCO_3} \rightarrow \mathrm{C_6H_5COONa} + \mathrm{H_2O} + \mathrm{CO_2}(y) \] Thus, gas $(y)$ is carbon dioxide.
Molar mass of $\mathrm{CO_2} = 44\,\text{g mol}^{-1}$.
Step 3: Calculating required sum.
\[ \text{Molar mass of } x + \text{Molar mass of } y = 2 + 44 = 46 \] Step 4: Final conclusion.
The required numerical value is $46$.