Let En=-18ε02me4n2h2 be the energy of the nth level of H-atom. If all the H-atoms are in the ground state and radiation of frequency (E2-E1)h falls on it,

(a) it will not be absorbed at all
(b) some of the atoms will move to the first excited state
(c) all atoms will be excited to the n = 2 state
(d) no atoms will make a transition to the n = 3 state

1. (b, d)

2. (a, d)

3. (b, c, d)

4. (c, d)

(1) Hint: The excitation of the atoms depends on the energy given to them.
When all the H-atoms are in the ground state and radiation of frequency (E2-E1)h falls on it, some of atoms will move to the first excited state and no atoms will make a transition to the n = 3 state.