Question

How many of following molecules will have degrees of freedom less than or equal to 5? (Ignore vibrational degrees of freedom)
$O_2$, $N_2$, $CO$, $C{l}_2$, $He$, $Ar$,$S{O}_2$, $C{S}_2$, $H_{2}O$

• A. 5
• B. 7
• C. 4
• D. 3

Answer 1

The correct option is B 7

Only the triatomic or polyatomic molecules with non linear shape will have more than five degrees of freedom. Out of the given molecules, only three molecules are there which are triatomic
$S{O}_2$, $C{S}_2$, $H_{2}O$

Out of these, $C{S}_2$ is linear so only two molecules are non linear. So these two molecules will have degrees of freedom greater than 5 and rest all molecules will have degrees of freedom less than or equal to 5.

There are 9 molecules given in total .

So, Number of gasesous molecules having degrees of freedom less than or equal to 5 are = 9-2= 7