The linear speed of the electron in the nth Bohr orbit,
Vn = \(\cfrac{e^2}{2ε_0nh}\)
∴ The linear momentum of the electron in the second orbit,
P2 = mev2 = \(\cfrac{m_e\,e^2}{4ε_0h}\)
\(\therefore\) The linear momentum of the electron in the third orbit,