In a hydrogen like atom, when an electron jumps from the M-shell to the L-shell, the wavelength of emitted radiation is $$\lambda $$. If an electron jumps from N-shell to the L-shell, the wavelength of emitted radiation will be:

A hydrogen atom, initially in the ground state is excited by absorbing a photon of wavelength 980$$\mathop A\limits^ \circ $$. The radius of the atom in the excited state, in terms of Bohr radius a₀ will be : (hc = 12500 eV$$\mathop A\limits^ \circ $$)

Consider the nuclear fission

Ne²⁰ $$ \to $$ 2He⁴ + C¹²

Given that the binding energy/ nucleon of Ne²⁰, He⁴ and C¹² are, respectively, 8.03 MeV, 7.07 MeV and 7.86 MeV, identify the correct statement -

Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At t = 0 it was 1600 counts per second and t = 8 seconds it was 100 counts per second. The count rate observed, as counts per second, at t = 6 seconds is close to -