Question

The correct order of bond length among the following is:
A. $C = O > C = C > C = N$
B. $C = O > C = N > C = C$
C. $C = C > C = N > C = O$
D. $C = N > C = C > C = O$

Answer 1

Hint: Bond length is defined as the average distance between the center of the nucleus to two covalently bonded atoms in a molecule and bond strength is measured by bond length, the greater the bond length weaker will be the bond strength.

Complete step by step answer:
In the above case, the order of bond length depends upon the size of oxygen, carbon, and nitrogen. Since oxygen, carbon, and nitrogen all belong to the same period i.e. period 2nd. Moving left to right or on moving in a period size of the atom decreases as there is an increase in effective nuclear charge. The size of oxygen-carbon and nitrogen decreases in the order given as:
Carbon > nitrogen > oxygen .
Hence the correct order of bond length among the given cases is :
$C = C > C = N > C = O$

So, the correct answer is Option C.

Additional information:
Bond length depends upon the various factors which are given below:
1. Size of atom: Bond length is directly proportional to the size of atoms present in a molecule. With the increase in the size of the atom, there is also an increase in bond length and vice-versa.
2. The multiplicity of bond: Bond length is inversely proportional to the bond length. As there is an increase in the multiplicity of bonds there is observed a decrease in bond length.i.e. the bond length of a molecule containing a single bond is higher than that in a double bond which is higher than that in a triple bond.
3.Types of hybridization: As we know the size of the s orbital is smaller, the greater the s character, the smaller will be the hydride orbitals thus smaller will be bond length.


Note: The bond length is expressed in terms of Angstrom (${A^ \circ }$) which is equal to ${10^{ - 10}}$ m or picometer which is equal to ${10^{ - 12}}$ m. Bond length is experimentally measured by either X-ray diffraction method or electron diffraction method. We can also determine it with the spectroscopic method.