This is from my chemistry assignment : 1) You have a tank of N2 gas. If the tank contains 11.65 L of the gas (at STP), how many molecules of N2 are in it?
can someone pls explain how I would answer this and what equation I would use ?

One of the hopes for solving the world's energy problem is to make use of the fusion reaction 21h +31h --> 42he + 10n + energy how much energy is released when 1 mol of deuterium is fused with 1 mol of tritium according to the above reaction? the masses of the atoms and the neutrons are as follows: 21h = 2.0140 amu 31h = 3.01605 amu 42he = 4.002603 amu 10n = 1.008665 amu. the speed of light is 2.9979 x 108 m/s.