Answer
No, not all $CH_4$ molecules have the same kinetic energy at 273 K. Instead, 273 K is a measure of the average kinetic energy when in reality, molecules have a range of kinetic energies.
Work Step by Step
No, not all $N_2$ molecules have the same velocity at 546 K. For example, the Maxwell-Boltzmann distribution shows that for a mole of gas at a certain temperature, there is a range of velocities molecules will move at instead of a single, uniform velocity.
