Question

Which of the following molecule(s) are likely to have highest degrees of freedom?

• A. $C{O}_2$
• B. $C{S}_2$
• C. $H_{2}O$
• D. $S{O}_2$

Answer 1

Answer: (C), (D)

$S{O}_2$

All the four melecules are triatomic but there is a difference that $C{O}_2$ and $C{S}_2$ are linear while $S{O}_2$ and $H_{2}O$ are non linear so they will have more degrees of freedom as triatomic non-linear molecule may rotate, about the three mutually perpendicular axes, (which the linear molecules can't ). Therefore, it possesses three degrees of freedom of rotation (while linear molecules posseses only two).
Also these non-linear molecules have three degrees of freedom of translation along the three co-ordinate axes. Hence it has six degrees of freedom.