An ionised \(H\)-molecule consists of an electron and two protons. The protons are separated by a small distance of the order of angstrom. In the ground state:

(a)	the electron would not move in circular orbits.
(b)	the energy would be \(2^{4}\) times that of a \(H\)-atom.
(c)	the electron's orbit would go around the protons.
(d)	the molecule will soon decay in a proton and a \(H\)-atom.

1. (a), (b)
2. (a), (c)
3. (b), (c), (d)
4. (c), (d)

The Bohr model for the spectra of a \(H\)-atom:

1. (a), (b)
2. (c), (d)
3. (b), (c)
4. (a), (d)

The Balmer series for the H-atom can be observed:
 

1. (b, c)

2. (a, c)

3. (b, d)

4. (c, d)

Let $E_n=\frac{-1}{8{\mathrm{\epsilon }}_0^2}\frac{m{e}^4}{n^2{h}^2}$ be the energy of the nth level of H-atom. If all the H-atoms are in the ground state and radiation of frequency $\frac{(E_2-E_1)}{h}$ 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)

The simple Bohr model is not applicable to He⁴ atom because

(a) He⁴ is an inert gas
(b) He⁴ has neutrons in the nucleus
(c) He⁴ has one more electron
(d) electrons are not subject to central forces

1. (a, c)

2. (a, c, d)

3. (b, d)

4. (c, d)