Atoms Class 12 MCQs Questions with Answers

1. When an atomic gas or vapour is excited at low pressure, by passing an electric current through it then

2. The first spectral series was discovered by

3. For the ground state, the electron in the H-atom has an angular momentum = h, according to the simple Bohr model. Angular momentum is a vector and hence there will be infinitely many orbits with the vector pointing in all possible directions. In actuality, this is not true,

4. Which of the following in a hydrogen atom is independent of the principal quantum number n? (The symbols have their usual meanings).

5.  The Balmer series for the H-atom can be observed

6. For a given value of n, the number of electrons in an orbit is

7. The first model of atom in 1898 was proposed by

8. On moving up in the energy states of a H-like atom, the energy difference between two consecutive energy states

9. According to Bohr’s model of hydrogen atom

10.  The spectral lines in the Brackett series arise due to transition of electron in hydrogen atom from higher orbits to the orbit with

11.  In a Rutherford scattering experiment when a projectile of
charge Z1 and mass M1 approaches a target nucleus of
charge Z2 and mass M2, the distance of closest approach
is r0. The energy of the projectile is

12. In the ground state in …A… electrons are in stable equilibrium while in …B… electrons always experiences a net force. Here, A and B refer to

13.  In Bohr’s model of an atom which of the following is an integral multiple of h/2π?

14.  For ionising an excited hydrogen atom, the energy required (in eV) will be

15. The Bohr model of atoms

16. 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,

17. The ratio between Bohr radii is

18.  In which of the following series, does the 121.5 nm line of the spectrum of the hydrogen atom lie ?

19. The hydrogen atom can give spectral lines in the Lyman, Balmer and Paschen series. Which of the following statement is correct?

20. The angular momentum of electrons in an atom produces