Hydrogen atom in ground state is excited by a monochromatic radiation of $$\lambda $$ = 975 $$\mathop A\limits^ \circ $$. Number of spectral lines in the resulting spectrum emitted will be

The binding energy per nucleon of and nuclei are 5.60 MeV and 7.06 MeV respectively. In the nuclear reaction

$${}_3^7Li + {}_1^1H \to {}_2^4He + _2^4He + Q$$

the value of energy Q released is

How does the Binding Energy per nucleon vary with the increase in the number of nucleons ?

An electron in hydrogen atom makes a transition n₁ $$ \to $$ n₂ where n₁ and n₂ are principal quantum numbers of the two states . Assuming Bohr's model to be valid, the time period of the electron in the initial state is eight times that in the final state. The possible values of n₁ and n₂ are