The root mean square (r.m.s) speed of oxygen molecules `(O_2)`
at a certain temperature T (degree absolute) is V. If the temperature is doubled and oxygen gas dissociates into atomic oxygen, the r.m.s speed remains unchanged.

Explanation

`V_("m s") = sqrt((3RT)/M)" or "V_("m s") prop sqrt(T/M)`
When oxygen gas dissociates into atomic oxygen its atomic mass M will remain half. Temperature is doubled. So, from Eq. (i) `V_("m s")` will become two times