What is the total number of electrons that can have the values $$n=2, l=1, s=1 / 2$$ in the electronic configuration $$1 s^2 2 s^2 2 p^3$$ ?

Calculate the wavelength associated with an electron moving with a velocity of $$10^6 \mathrm{~m} / \mathrm{s}$$ (mass of electron $$=9.1 \times 10^{-31} \mathrm{~kg}, h=6.6 \times 10^{-34} \mathrm{~kg} \mathrm{~m}^2 \mathrm{~s}^{-1}$$ )

Which of the following pairs is not correctly matched?