Topicwise Questions - Atomic Structure

1. Which of the following defines the Mass number of an atom?

  1. number of protons + number of electrons
  2. number of neutrons + number of electrons
  3. number of protons + number of neutrons
  4. number of electrons

2. Who is credited with the discovery of electron?

  1. JJ Thomson
  2. James Chadwick
  3. Ernest Rutherford
  4. Niels Bohr

3. An atom has a mass number of 37 and atomic number 17. How many protons does it have?

  1. 20
  2. 17
  3. 54
  4. 21

4. Which of the following mostly accounts for the mass of an atom?

  1. neutrons
  2. neutron and proton
  3. electron and proton
  4. electron and neutron

5. Within an atom, the nucleus when compared to the extra nuclear part is

  1. bigger in volume and heavier in mass
  2. smaller in volume but heavier in mass
  3. smaller in volume and lighter in mass
  4. same size

6. What would be the atomic number of the element in whose atom the K and L shells are full?

  1. 10
  2. 12
  3. 14
  4. 16

7. Which metal was used by Rutherford in his alpha-scattering experiment?

  1. gold
  2. platinum
  3. silver
  4. lead

8. An element has an electronic configuration of 2, 8, 7. Its valency is

  1. 2
  2. 7
  3. 3
  4. 1

9. During a chemical reaction, atomic number

  1. changes
  2. remains same
  3. changes and then is restored
  4. changes alternately

10. Which isotope of hydrogen contains only one proton and no neutron in its nucleus?

  1. protium
  2. deuterium
  3. tritium
  4. None of the above

11. Who of the following was awarded the Nobel Prize for his measurement of elementary electronic charge?

  1. Rutherford
  2. Robert Millikan
  3. James Chadwick
  4. JJ Thomson

12. How are the subshells in an atom labelled?

  1. s, p, d, f, g
  2. s, p, f, g, d
  3. s, f, g, d, f
  4. s, d, g, p, f

13. The isotopes of neutral atoms of an element differ in

  1. Atomic number
  2. Mass number
  3. Number of electrons
  4. Chemical properties

14. The electronic configuration of an atom having atomic number 20 is

  1. 2, 8, 8, 2
  2. 2, 8, 10
  3. 2, 6, 8, 4
  4. 2, 4, 8, 6

15. Almost the entire mass of an atom is concentrated in the

  1. proton
  2. electrons
  3. nucleus
  4. neutrons

16. An atom differs from its ion in

  1. Nuclear charge
  2. Mass number
  3. Number of electrons
  4. Number of neutrons