The correct option is C 5
Number of degree of freedom of a molecule=3N
where, N is the number of atoms.
Therefore,
Degree of freedom = 3 × 2
= 6
In 6, 3 corresponds to translation motion because a molecules can move in all three axis like x, y, z.
Number of vibrational degree of freedom for linear molecule is 3N-5
Therefore,
Vibrational degree of freedom = 3×2−5
= 1
Hence, we have 2 rotational degree of freedom.
At normal temperature, molecule will not have sufficient energy to exhibit vibrational motion.
Therefore, at normal temperature degree of freedom is 5