MULTIPLE CHOICE QUESTIONS:

MULTIPLE CHOICE QUESTIONS: (MCQ’s)

1. The combining capacity of an atom is called _____________.

(a) Atomicity
(b) Volume
(c) Valency 
(d) Equation

2. __________ is the equal to number of protons.

(a) Mass number
(b) Atomic mass
(c) Neutral charges
(d) Atomic number

 3. ___________ is the equal to sum of protons and neutrons.

(a) Mass number
(b) Atomic mass 
(c) Atomic number
(d) Valency

4. Atoms of same element with same atomic number but different mass number are called ___________.

(a) Isobars
(b) Isotopes
(c) Protons
(d) None of these

5. Canal rays are positively charged radiations which led to the discovery of positively charged sub –atomic particle is called ____________.

(a) Neutron
(b) Electron
(c) Proton
(d) None of these

6. The electronic configuration of Chlorine is _____________.

(a) 2, 7 
(b) 2, 8, 8
(c) 2, 8, 7
(d) 2, 7, 8

7. The electrons present in the outermost shell are called _____________.

(a) Valency electrons
(b) Duplet electrons
(c) Octet electrons
(d) Valence electron

8. Which one of the following is a correct electronic configuration of Sodium?

(a) 2, 1, 8
(b) 2, 8 
(c) 2, 1, 8
(d) 2, 8, 1

9. Electrons present in the outermost shell of an atom are called _____________.

(a) Valence electrons
(b) Protons
(c) Electrons
(d) Neutrons

10. Mass of an atom is concentrated in the ___________.

(a) Proton
(b) Nucleus
(c) Neutron
(d) Nucleons

11. Protons and neutrons present in the nucleus are called ____________.

(a) Atoms
(b) Molecules
(c) Nucleons
(d) Isobars

 12. When atoms of different element have same mass number but different atomic number such atoms are called ______________.

(a) Isobars 
(b) Isotopes
(c) Nucleons
(d) Protons

13.  The  isotope of _____ is used  in the treatment of goitre.

(a)  Radium
(b) Uranium
(c) Thorium
(d) Iodine

14. ___________ isotope is used in the treatment of cancer.

(a) Radium
(b) Thorium
(c) Iodine
(d) Cobalt

15. Rutherford’s ‘alpha (α) particles scattering experiment’ resulted in the discovery of ____
(a) Electron
(b) Proton
(c) Nucleus in the atom
(d) Atomic mass

16. The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?
(a) 13
(b) 10
(c) 14
(d) 16

17. The first model of an atom was given by ____
(a) N. Bohr
(b) E. Goldstein
(c) Rutherford
(d) J.J. Thomson

18.An atom with 3 protons and 4 neutrons will have a valency of _____
(a) 3
(b) 7
(c) 1
(d) 4

19. Which of the following statements about Rutherford’s model of atom are correct?
(i) Considered the nucleus as positively charged.
(ii) Established that the a-particles are four times as heavy as a hydrogen atom.
(iii) Can be compared to solar system.
(iv) Was in agreement with Thomson’s model.
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) only (i)

20. How many electrons are present in M-shell of an element with atomic number 20?
(a) 5
(b) 8
(c) 12
(d) 18

21. There are two atomic species X and Y, such that
MCQ Questions for Class 9 Science Chapter 4 Structure of the Atom with Answers
 Which of the following statements is true about X and Y?
(a) X and Y are isobars.
(b) X and Y have different chemical properties.
(c) X and Y have different physical properties.
(d) All of these.

22. The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?
(a) 13
(b) 10
(c) 14
(d) 16

23. An alpha particle is also known as ____
(a) Subatomic particle
(b) An unionised helium atom
(c) A neutral particle
(d) A doubly charged helium ion

24. The charge on an electron is equal to ____
(a) 1.6 × 10-19 C of -ve charge
(b) 2.6 × 10-19 C of -ve charge
(c) 1.6 × 10-22 C of -ve charge
(d) 1.6 × 10-23 C of -ve charge

25. Which of the following isotope is used in the treatment of blood cancer?
(a) P−32
(b) I−131
(c) Co−60
(d) None of these 

26. Isobars do not differ in the number of ____
(a) Protons
(b) Electrons
(c) Neutrons
(d) Nucleons

27. Which of the following correctly represents the electronic distribution in the Mg atom?
(a) 3, 8, 1
(b) 2, 8, 2
(c) 1, 8, 3
(d) 8, 2, 2

 
28. ____was interested in knowing how the electrons are arranged within an atom.
(a) N. Bohr
(b) E. Goldstein
(c) Rutherford
(d) J.J. Thomson
 
29. Neutrons are present in the nucleus of all atoms except ______
(a) Hydrogen
(b) Oxygen
(c) Argon
(d) Nitrogen
 
30. An isotope of _____is used s a fuel in nuclear reactors
(a)  Radium
(b) Uranium
(c) Thorium
(d) None of these

 Answers:
1. (c) Valency
2. (d) Atomic number
3. (a) Mass number
4. (b) Isotopes
5. (c) Proton
6. (c) 2, 8, 7
7.  (d) Valence electron
8.  (d) 2, 8, 1
9.  (a) Valence electrons
10. (b) Nucleus
11. (c) Nucleons
12. (a) Isobars
13. (d) Iodine
14. (d) Cobalt
15.(c) Nucleus in the atom
16.(b) 10
17.(d) J.J. Thomson
18.(c) 1
19. (a) (i) and (iii)
20. (b) 8
21. (c) X and Y have different physical properties.
22. (b) 10
23. (d) a doubly-charged helium ion
24. (a) 1.6 × 10-19 C of -ve charge
25. (a) P−32
26. (d) nucleons
27. (b) 2, 8, 2
28.(c) Rutherford
29.(a) Hydrogen
30.(b) Uranium