- What is the centre of an atom called?
(a) The protons
(b) The nucleus
(c) The electrons
2. What is the charge on an electron?
(a) One positive
(b) No charge
(c) One negative
3. Which of the three sub-atomic particles is the lightest?
(a) The proton
(b) The neutron
(c) The electron
4. If atoms contain charged particles, why do they not have a charge?
(a) They contain the same number of protons as electrons
(b) The charge is locked away in the nucleus
(c) They contain equal numbers of protons and neutrons
5. What is the atomic number of an atom equal to?
(a) The number of protons in the nucleus
(b) The number of neutrons in the nucleus
(c) The numbers of protons and neutrons in the nucleus
6. Where are the electrons inside an atom?
(a) The electrons are in the nucleus of an atom
(b) They are arranged in energy levels
(c) The electrons are spread equally throughout the atom
7. How many neutrons does this atom of carbon have?
8. Which of the following defines the Mass number of an atom?
a. number of protons + number of electrons
b. number of neutrons + number of electrons
c. number of protons + number of neutrons
d. number of electrons
9. Who is credited with the discovery of electron?
a. JJ Thomson
b. James Chadwick
c. Ernest Rutherford
d. Niels Bohr
10. An atom has a mass number of 37 and atomic number 17. How many protons does it have?
11. Which of the following mostly accounts for the mass of an atom?
b. neutron and proton
c. electron and proton
d. electron and neutron
12. Within an atom, the nucleus when compared to the extra nuclear part is –
a. bigger in volume and heavier in mass
b. smaller in volume but heavier in mass
c. smaller in volume and lighter in mass
d. same size
13. Which metal was used by Rutherford in his alpha-scattering experiment?
14. Almost the entire mass of an atom is concentrated in the
15. The proton is heavier than an electron by –
a. 187 times
b. 1837 times
c. 3837 times
d. 2827 times
16. Which of the following is not a fundamental particle?
c. Alpha particle
17. Which one among the following most correctly determines the atomic number of an element?
a. Number of protons
b. Number of protons and electrons
c. Number of ions
d. Number of nucleons
18. The number of protons in a negatively charged atom (anion) is –
a. more than the atomic number of the element
b. less than the atomic number of the element
c. more than the number of electrons in the atom
d. less than the number of electrons in the atom
19. Which of the following has a positive charge?
20. Rutherford carried out experiments in which a beam of alpha particles was directed at a thin piece of metal foil. From these experiments he concluded that:
(a) electrons are massive particles.
(b) the positively charged parts of atoms are moving about with a velocity approaching the speed of light.
(c) the positively charged parts of atoms are extremely small and extremely heavy particles.
(d) the diameter of an electron is approximately equal to that of the nucleus.
(e) electrons travel in circular orbits around the nucleus.
21. Who discovered electrons?
(a) J.J Thomson
(b) Neils Bohr
(c) James Chadwick
22. Consider an atom with atomic number 17 and mass number 37. What is the number of protons?