Under standard conditions the density of the helium and nitrogen mixture equals `rho = 0.60 g//1`. Find the concentration of helium atoms in the given mixture.

Explanation

Let `n_1 `= density of `He` amtoms, `n_2` - number density of `N_2` molecules
Then `rho = n_1 m_1 + n_2 m_2`
where `m_1` = mass of `He` atom, `m_2`= mass of `N_2` molecule also `p = (n_1 + n_2) kT`
From these two equations we get
`n_1 = ((p)/(kT) -(rho)/(m_2))//(1 - (m_1)/(m_2))`.