Dual Nature Of Radiation

A proton is fired from very far away towards a nucleus with charge Q = 120e, where e is the electronic charge. It makes a closest approach of 10 fm to the nucleus. The de Broglie wavelength (in units of fm) of the proton at its start is ____________. (Take the proton mass, \({m_p} = (5 \times 3) \times {10^{ - 27}}\) kg; \(h/e = 4.2 \times {10^{ - 15}}\) J.s/C; \({1 \over {4\pi {\varepsilon _0}}} = 9 \times {10^9}\) m/F; 1 fm = 10¹⁵ m.)