Chemistry Chemical Bonding NUMS 2024
PMDC Verified Question 17 of 102
In \( \text{CH}_3\text{Cl} \), bond length of C-Cl is 176.7pm and covalent radius of Cl atom is 99.4pm, the covalent radius of carbon atom is:
A
66.3 pm
B
276.1 pm
C
175.4 pm
D
77.3 pm
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: 77.3 pm
Concept:

The bond length of a single covalent bond is approximately the sum of the covalent radii of the two bonded atoms.

Formula:

$$ \text{Bond Length}_{(\text{C-Cl})} = \text{Radius}_{(\text{C})} + \text{Radius}_{(\text{Cl})} $$

Solution:

  • We are given the total bond length: 176.7 pm.


  • We are given the radius of Chlorine: 99.4 pm.


  • Rearranging the formula to find Carbon's radius:
    $$ \text{Radius}_{(\text{C})} = \text{Bond Length} - \text{Radius}_{(\text{Cl})} $$


  • $$ \text{Radius}_{(\text{C})} = 176.7 - 99.4 = 77.3 \text{ pm} $$


Why other options are incorrect:

  • Option A, Option B, Option C: These are the results of incorrect arithmetic (e.g., adding instead of subtracting, or simple subtraction errors).

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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