A 5.0-liter gas tank holds 1.4 moles of helium (He) and 0.70 moles of oxygen (O2), at a

temperature of 260 K. The atomic masses of helium and oxygen are 4.0g/mol and 16.0g/mol,

respectively. The total random translational kinetic energy of the gas in the tank is

(1) 7.4 kJ.

(2) 6.1 kJ.

(3) 7.6 kJ.

(4) 6.8 kJ

(5) 9.1 kJ