Question

 

Which compound has the shortest carbon-carbon bond length?

1. CH₃CH₃
2. CH₂CH₂
3. HCCH
4. All bond lengths are the same.

Answer 1

Concepts and reason

Bond length: It is the average distance between the two bonded atoms.

Bond length is inversely proportional to the bond order.

Bond order is defined as a measure of the number of electron pairs shared between the two bonded atoms.

Fundamentals

The fundamental values of bond length for the organic molecules are as follows:

S.NO	Molecule	Bond length (A0)
1	C – C	1.54
2	C =C	1.34
3	${\rm{C}} \equiv {\rm{C}}$	1.20

Greater the bond order, shorter the bond length.

The wrong choices are given below

$\begin{array}{l}\\{\rm{A) C}}{{\rm{H}}_3}{\rm{C}}{{\rm{H}}_3}\\\\{\rm{B) C}}{{\rm{H}}_2}{\rm{CH}}2\\\\{\rm{D) All bond lengths are the same}}\\\end{array}$

The correct option from the given choices is

${\rm{C) HCCH}}$

Ans:

The correct option is

$\begin{array}{l}\\A) C{H_3}C{H_3}\\\\B) C{H_2}CH2\\\\C) HCCH\\\\D) All bond lengths are the same\\\end{array}$