### MCQs of Atoms

Showing 1 to 10 out of 146 Questions
1.
An electron with energy 12.09 eV strikes hydrogen atom in ground state, and gives its all energy to the hydrogen atom. Therefore, hydrogen atom is excited to _____ state.
 (a) fourth (b) third (c) second (d) first
2.
For the first orbit of hydrogen atom the minimum excitation potential is _____ C.
 (a) 13.6 (b) 3.4 (c) 10.2 (d) 3.6
3.
The frequency of characteristics X-ray determines _____, property of the target
 (a) atomic weight (b) atomic number (c) melting point (d) conductivity
4.
A hydrogen atom absorbs 12.1 eV of energy and excited to higher energy level. How many photons are emitted during downward transition. Assume during each downward transition, one photon is emitted.
 (a) 1 or 3 (b) 2 or 3 (c) 1 or 2 (d) 5 or more.
5.
The radius of second orbit in an atom of hydrogen is R. What is its radius in third orbit ?
 (a) 3R (b) 2.25R (c) 9R (d) $\frac{R}{3}$
6.
The ratio of energies of electron in the first excited state to its second excited state in H-atom is _____ .
 (a) 1 : 4 (b) 4 : 9 (c) 9 : 4 (d) 4 : 1
7.
In an hydrogen atom, the radiation emitted is found to be in ultraviolet region due to transition between n = 4 to n = 3. During which of the following transitions will the light emitted be in infrared region ?
 (a) 2 → 1 (b) 3 → 2 (c) 4 → 2 (d) 5 → 4
8.
 (a) $\frac{-{e}^{2}}{4\mathrm{\pi }{\in }_{0}\mathrm{r}}$ (b) $\frac{{e}^{2}}{8\mathrm{\pi }{\in }_{0}\mathrm{r}}$ (c) $-\frac{{e}^{2}}{8\mathrm{\pi }{\in }_{0}\mathrm{r}}$ (d) $\frac{{e}^{2}}{4\mathrm{\pi }{\in }_{0}\mathrm{r}}$
9.
An α-particle of 10 MeV is moving forward for a head on collision. What will be the distance of closest approach from the nucleus of atomic number Z = 50 ?
 (a) 1.44 × 10-14 m (b) 2.88 × 10-14 m (c) 0.53 × 10-10 m (d)
10.
According to Bohr's hypothesis, the angular momentum of the electron in any stationary orbit of radius r is proportional to _____ .
 (a) r (b) $\frac{1}{r}$ (c) $\sqrt{r}$ (d) ${r}^{2}$
Showing 1 to 10 out of 146 Questions