Chemistry Chemical Bonding ETEA 2023
PMDC Verified Question 28 of 102
The bond length between double bonded carbon atoms is:
A
1.34 \( \text{\AA} \)
B
1.10 \( \text{\AA} \)
C
1.54 \( \text{\AA} \)
D
1.82 \( \text{\AA} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: 1.34 \( \text{\AA} \)
Concept:

As bond order increases (single -> double -> triple), the atoms are pulled closer together, decreasing the bond length.

Formula:

$$ \text{C-C} > \text{C=C} > \text{C}\equiv\text{C} $$

Solution:

  • Experimental data shows the standard C-C single bond length (e.g., in ethane) is 1.54 \( \text{\AA} \).


  • The standard C=C double bond length (e.g., in ethene) is 1.34 \( \text{\AA} \).


  • The standard C\( \equiv \)C triple bond length (e.g., in ethyne) is 1.20 \( \text{\AA} \).


  • Therefore, the correct value for a double bond is 1.34 \( \text{\AA} \).


Why other options are incorrect:

  • Option C: This is the bond length for a single C-C bond.
  • Option B & Option D: These do not correspond to standard carbon-carbon bond lengths.

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