Question

On complete combustion, 0.3 g of an organic compound gave 0.2 g of CO₂ and 0.1 g of H₂O. The percentage composition of carbon and hydrogen in the compound, respectively, is:

• A. 4.07% and 15.02%
• B. 18.18% and 3.70%
• C. 15.02% and 4.07%
• D. 3.70% and 18.18%

Answer 1

The Correct Option is B

To find the percentage composition of carbon and hydrogen in an organic compound, we need to analyze the products of its complete combustion. The given data is: 

• Mass of the organic compound (sample) = 0.3 g
• Mass of CO₂ produced = 0.2 g
• Mass of H₂O produced = 0.1 g

1. Determine the mass of carbon in CO₂:
   • The molar mass of CO₂ = 44 g/mol (C = 12, O = 16 × 2 = 32)
   • Mass of carbon in 44 g of CO₂ = 12 g
   • Therefore, in 0.2 g of CO₂:
2. Determine the mass of hydrogen in H₂O:
   • The molar mass of H₂O = 18 g/mol (H = 1 × 2 = 2, O = 16)
   • Mass of hydrogen in 18 g of H₂O = 2 g
   • Therefore, in 0.1 g of H₂O:
3. Calculate the percentage of carbon and hydrogen in the compound:
   • Percentage of Carbon = \(\frac{0.0545}{0.3} \times 100 = 18.18\%\)
   • Percentage of Hydrogen = \(\frac{0.0111}{0.3} \times 100 = 3.70\%\)
4. Cross-verification with options:
   • The calculated percentages are 18.18% (Carbon) and 3.70% (Hydrogen).
   • This matches with the option: 18.18% and 3.70%.

Therefore, the correct answer is 18.18% and 3.70%.