The number of molecules in one litre of an ideal gas at 300 K and 2 atmospheric pressure

Hi, I have a question and I hope anyone could answer it:

The number of molecules in one litre of an ideal gas at 300 K and 2 atmospheric pressure with mean kinetic energy 2 × 10^–9 J per molecules is :

(1) 0.75 × 10¹¹

(2) 3 × 10¹¹

(3) 1.5 × 10¹¹

(4) 6 × 10¹¹