Question: how many molecules are in 1 mole of no2?
Answer: In order to have one mole of things, let's say particles, you need to have 6.022⋅1023 particles → this is known as Avogadro's constant and acts as the definition of the mole. So, in one mole of nitrogen gas you have 6.022⋅1023 molecules of nitrogen gas, N2 .