Which one of the following statements is not correct?

Question: Which one of the following statements is not correct?

In a sample of air at a given temperature ________

1. the nitrogen and oxygen molecules have the same average kinetic energy.
2. all the molecules are moving.
3. the nitrogen and oxygen molecules have the same average speed.
4. some nitrogen molecules are moving faster than some oxygen molecules.
5. some nitrogen molecules are moving slower than some oxygen molecules.

Answer and Explanation

at constant temperature
kinetic energy = (3*K*T)/2
so, kinetic energy is same for every gas
so, statement A is correct

at constant temperature Vav depends only on molar mass of gas
since, molar mass of N2 and O2 is not same
so, Vav is not same for N2 and O2
so, statement C is not correct

always, some N2 move faster and some slower by O2 molecules

Answer : C