Assertion : Percentage of carbon in `Na_2CO_3` is 11.32%.
Reason: % of carbon `=("Mass of carbon element")/("Molecular mass of" Na_(2)CO_(3)) xx 100`

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question regarding the percentage of carbon in sodium carbonate (Na₂CO₃), we will follow these steps:

### Step 1: Identify the formula for calculating the percentage of an element in a compound.
The formula to calculate the percentage of an element in a compound is:
\[ \text{Percentage of element} = \left( \frac{\text{Mass of element}}{\text{Molecular mass of compound}} \right) \times 100 \]

### Step 2: Determine the mass of carbon in Na₂CO₃.
In the compound Na₂CO₃, there is one carbon atom. The atomic mass of carbon (C) is approximately 12 g/mol. Therefore, the mass of carbon in Na₂CO₃ is:
\[ \text{Mass of carbon} = 12 \text{ g/mol} \]

### Step 3: Calculate the molecular mass of Na₂CO₃.
To find the molecular mass of Na₂CO₃, we need to sum the atomic masses of all the atoms in the compound:
- Sodium (Na): 23 g/mol (2 atoms)
- Carbon (C): 12 g/mol (1 atom)
- Oxygen (O): 16 g/mol (3 atoms)

Calculating the total:
\[ \text{Molecular mass of Na₂CO₃} = (2 \times 23) + (1 \times 12) + (3 \times 16) \]
\[ = 46 + 12 + 48 = 106 \text{ g/mol} \]

### Step 4: Substitute the values into the percentage formula.
Now we can substitute the mass of carbon and the molecular mass of Na₂CO₃ into the percentage formula:
\[ \text{Percentage of carbon} = \left( \frac{12}{106} \right) \times 100 \]

### Step 5: Calculate the percentage.
Calculating the above expression:
\[ \text{Percentage of carbon} = \left( \frac{12}{106} \right) \times 100 \approx 11.32\% \]

### Conclusion:
The assertion that the percentage of carbon in Na₂CO₃ is 11.32% is correct. The reason provided is also correct as it accurately describes the method used to calculate the percentage.

### Final Answer:
Both the assertion and the reason are correct.

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