The average kinetic energy of the molecules in a gas sample depends only on the temperature, t. but given the same kinetic energies, a lighter molecule will move faster than a heavier molecule. what is the rms speed of o2 molecules at 423 k?

The root mean square (rms) speed of a gas is given by

where R is the gas constant, T the absolute temperature of the gas and  is the molar mass of the gas.

For molecular oxygen , the molar mass is , so since the temperature of the gas in the problem is T=423 K, the rms speed of its molecules is

The answer is a) taiga because taigas are cold