The molecules of which of the following gases have the largest mean average K.E. at `250^(@)C` ?

Which of the following gases will have hightest average molecular speed at 25^(@)C ?

At 298 k, which of the following gases has the lowest average molecular speed?

which out of the following will have largest value of K_(sp) ?

At which of the following temperatures would the molecules of a gas have twice the average kinetic energy they have at 20^(@)C ?