Class 9 Science MCQ Chapter 4 Structure of the Atom, Class 9 Science MCQ Question Answer, Class 9 Science Multiple Choice Question Answer to each chapter is provided in the list of SCERT Science Class 9 Objective Types Question Answer so that you can easily browse through different chapters and select needs one. Class 9 Science MCQ Chapter 4 Structure of the Atom Question Answer can be of great value to excel in the examination.
SCERT Class 9 Science MCQ Chapter 4 Structure of the Atom
SCERT Class 9 Science MCQ Chapter 4 Structure of the Atom Notes covers all the exercise questions in SCERT Science Textbooks. The NCERT Class 9 Science MCQ Chapter 4 Structure of the Atom provided here ensures a smooth and easy understanding of all the concepts. Understand the concepts behind every chapter and score well in the board exams.
Structure of the Atom
Chapter – 4
Multiple Choice Questions & Answers
1. Particles are doubly – charged –
(a) hydrogen ions
(b) Helium ions
(c) Lithium ions
(d) Boron ions
Ans. (b) Helium ions .
2. In Rutherford’s experiment, he was taken gold foil. This gold foil was about
(a) 1000 atoms thick
(b) 2000 atoms thick
(c) 3000 atoms thick
(d) 4000 atoms thick
Ans. (a) 1000 atoms thick.
3. The mass of a particle has
(a) 2u
(b) 3u
(c) 4u
(d) 5u
Ans. (c) 4u.
4. the mass of proton has approximately
(a) 5000 times of the electrons
(b) 4000 times of the electrons
(c) 3000 times of the electrons
(d) 2000 times of the electrons
Ans. (d) 2000 times of the electrons.
5. Who was the first one to propose a model for the structure of an atom.
(a) J J Thomson
(b) Rudherford
(c) E. Goldstein
(d) Bohr
Ans. (a) J J Thomson.
6. In Rutherford’s experiment, A very small fraction of a particles were deflected by –
(a) 60⁰
(b) 90⁰
(c) 120⁰
(d) 180⁰
Ans. (d) 180⁰.
7. Which of the following energy level is correct respectively?
(a) LKMN
(b) HKLMN
(c) KLMN
(d) JKLMN
Ans. (c) KLMN.
8. The formula of the maximum number of electrons present in a shell is
(a) 3n²
(b) 2n²
(c) 3n
(d) 2n
(Where is the number orbit)
Ans. (b) 2n².
9. What is the maximum number of electron in N shell?
(a) 32
(b) 18
(c) 10
(d) 2
Ans. (a) 32.
10. What is the maximum number of electron in L shell?
(a) 32
(b) 10
(c) 18
(d) 8
Ans. (d) 8.
11. The maximum number of electrons that can be accommodated in the outer most orbit is —
(a) 10
(b) 8
(c) 6
(d) 4
Ans. (b) 8.
12. An atom has 8 electrons in outermost orbit. What is its valency?
(a) 0
(b) 1
(c) 2
(d) 3
Ans. (a) 0
13. An atom has 1 electron is outermost orbit. What is its valency?
(a) 0
(b) 1
(c) 2
(d) 3
Ans. (b) 1
14. An atoms has 7 electron in outermost orbit. What is its valency?
(a) 3
(b) 2
(c) 1
(d) 0
Ans. (c) 1
15. Who discovered neutron?
(a) Neils Bohr
(b) J. Chadwick
(c) Dalton
(d) E. Goldstein
Ans. (b) J. Chadwick.
Very Short Answer Type Questions
1. What is called canal rays?
Ans. Before the electron was identified E. Goldstein discovered the presence of new radiations in a gas discharge called them canal rays.
2. Who identified the electron?
Ans. J. J. Thomsom identified the electron.
3. What is the mass of a proton?
Ans. The mass of proton is approximately2000 times as that of the electron.
4. Why is the atom as a whole electrically neutral?
Ans. The negative and positive charges are equal a magnitude. So the atom as a whole is electrically neutral.
5. What are called energy levels?
Ans. The orbits or shells are called energy levels.
6. What do you mean by the mass of an atom?
Ans. The sum of the masses of protons and neutrons present in the nucleus as known as the mass of an atom.
7. The mass of sodium atom is 23u. Calculate the atomic number, number of protons, (ii) Number of neutrons, and number of electrons of sodium.
Ans. The number of protons of sodium is = 11
So, the number of electrons of sodium is = 11
So, the atomic number of sodium is = 11
The number of neutron of sodium is = 23-11
=12u.
8. The mass of Aluminium atom is 27u. Calculate the protons, electrons, atomic number and neutron of Aluminium?
Ans. The number of protons of Aluminium is = 13
So, the number of electrons of Aluminium is = 13
So, the number of neutrons of Aluminium is = 27-13
= 14u
So, the atomics number of Aluminium is = 13
9. What do you mean by valence electrons?
Ans. The electrons present in the outermost shell of an atom are known as the valence electron.
10. What is called valency?
Ans. An atom of each element has a definite combining capacity is called its valency.
11. What do you mean by atomic number?
Ans. The total number of protons in an atom is called atomic number.
12. What is called nucleus?
Ans. The protons and neutrons are also called nucleons.
13. The chlorine has atomic number 37u and mass number 37 u. How can be written with Symbol?
Ans. ³⁵/₁₇ Cl
14. What do you mean by isotopes?
Ans. The atom of the same element having the same atomic number but different mass numbers. It is called isotopes.
15. What do you mean by Isobars?
Ans. Atoms of different elements with different atomic numbers, which have the same mass number are known as Isobars.
16. Write the Isotope of hydrogen.
Ans. (i) protium
(ii) deuterium
(iii) tritium
17. Write the number of neutrons of hydrogen’s isotope.
Ans. (i) protium has 1 neutron.
(ii) deuterium has 2 neutron.
(iii) tritium has 3 neutron.
18. Write the atomic number of hydrogen’s isotope.
Ans. (i) Atomic number of protium is 1.
(ii) Atomic number of deuterium is 1.
(iii) Atomic number of tritium is 1.
19. Write the isotope of chlorine.
Ans. ³⁵/₁₇Cl and ³⁷/₁₇ Cl.
20. Write the isotope of carbon.
Ans.¹²/₆ C and ¹⁴/₆ C.
21. Mention one example of Isobar.
Ans. ⁴⁰/₂₀ Ca and ⁴⁰/₁₈ Ar.
22. Write the electron distribution in various shells of Argon.
Ans. in shell K = 2
in shell L=8
in shell L=8
23. What is the valency of Florine?
Ans. 1.
24. Write an using of isotope of uranium.
Ans. An isotope of uranium is used as a fuel in nuclear reactors.
25. Write an using of isotope of cobalt.
Ans. An isotope of cobalt is used in the treatment of cancer.
26. Write an using of isotope of iodine.
Ans. An isotope of iodine is used in the treatment of goitre.
27. Which of the element has no neutron?
Ans. hydrogen.
