CBSE Class 9 Science Structure of Atom MCQs

Structure of Atom Class 9 MCQ: This collection of multiple-choice questions (MCQs) from Chapter 4: Structure of Atom is designed for Class 9 Science students following the CBSE curriculum. Each question is provided with an answer and strictly follows the latest CBSE Class 9 Science syllabus (2025–26).

These MCQs help students strengthen their understanding of the chapter and prepare effectively for exams with the right level of difficulty. Along with these, students can also access free NCERT Solutions for Class 9 Science and CBSE Class 9 Notes to build a stronger foundation in Science.

CBSE Class 9 Science Structure of Atom MCQ

Class 9 students are encouraged to utilize the following set of multiple choice questions (MCQs) along with their respective answers for Chapter 4: “Structure of Atom” in their science curriculum. These MCQs have been curated to assist students in their exam preparation and are designed to enhance their understanding of the subject matter. By engaging with these questions, students can effectively test their knowledge and improve their performance in examinations.

Question 1: Which of the following is NOT a characteristic of atoms?

A) Smallest unit of matter are Atoms.

B) Atoms cannot be divided further by ordinary chemical means.

C) Atoms always exist in isolation, never forming compounds.

D) Atoms combine to form molecules.

Answer:

C) Atoms always exist in isolation, never forming compounds.

Question 2:

Which subatomic particle carries a negative charge?

A) Proton

B) Neutron

C) Electron

D) Nucleus

Answer: C) Electron

Question 3:

What is the atomic number of an element?

A) The total number of protons & neutrons in the nucleus.

B) The total number of electrons in the outermost shell.

C) The total number of protons in the nucleus.

D) The total number of neutrons in the nucleus.

Answer: C) The total number of protons in the nucleus.

Question 4:

What is the mass number of an atom?

A) The total number of electrons in the atom.

B) The number of protons in the nucleus.

C) The sum of protons and neutrons in the nucleus.

D) The number of shells in the atom’s electron cloud.

Answer: C) The sum of protons and neutrons in the nucleus.

Question 5:

When atoms share electrons what type of bond is formed?

A) Ionic bond

B) Covalent bond

C) Metallic bond

D) Hydrogen bond

Answer: B) Covalent bond

Question 8: What representation accurately corresponds to 360 grams of water?

(i) 2 moles of water

(ii) 20 moles of water

(iii) 6.022 × 10^23 molecules of water

(iv) 1.2044 × 10^25 molecules of water

(a) (i)

(b) (i) and (iv)

(c) (ii) and (iii)

(d) (ii) and (iv)

Answer: (d) (ii) and (iv)

Question 9: Which statement below does not align with the nature of an atom?

(a) Atoms are unable to exist independently.

(b) Atoms constitute the fundamental units from which molecules and ions are constructed.

(c) Atoms inherently possess a neutral charge.

(d) Atoms independently combine in vast quantities to form the tangible matter we perceive.

Answer: (d) Atoms independently combine in vast quantities to form the tangible matter we perceive.

Question 10: What is the significance of 1 u or 1 amu?

(a) 1/12th the mass of a C-12 atom

(b) The mass of a C-12 atom

(c) The mass of an O-16 atom

(d) The mass of a Hydrogen molecule

Answer: (a) 1/12th the mass of a C-12 atom

Structure of Atom Class 9 MCQ with Answers – Exam Level Questions

Question 1: Which subatomic particle has a negative charge?

A) Proton

B) Neutron

C) Electron

D) Nucleus

Answer: C) Electron

Question 2: What is the atomic number of an element that has 8 protons and 9 neutrons?

A) 8

B) 9

C) 17

D) 1

Answer: C) 17

Question 3: The nucleus of an atom is composed mainly of:

A) Protons and electrons

B) Neutrons and electrons

C) Protons and neutrons

D) Neutrons only

Answer: C) Protons and neutrons

Question 4: Which of the following statements about isotopes is true?

A) Isotopes have the same number of protons but different numbers of neutrons.

B) Isotopes have the same number of neutrons but different numbers of protons.

C) Isotopes have the same number of protons and neutrons.

D) Isotopes have different numbers of protons and electrons.

Answer: A) Isotopes have the same number of protons but different numbers of neutrons.

Question 5: Who proposed the planetary model of the atom?

A) Ernest Rutherford

B) J.J. Thomson

C) Niels Bohr

D) John Dalton

Answer: C) Niels Bohr

MCQ Questions for Class 9 Science

• Matter in Our Surroundings
• Is Matter Around Us Pure
• Atoms and Molecules
• The Fundamental Unit of Life
• Tissues
• Motion

Question 6: The mass number of an atom is determined by the total number of:

A) Electrons

B) Protons

C) Neutrons

D) Nucleons

Answer: D) Nucleons

Question 7: What is the charge of a neutron?

A) Positive

B) Negative

C) Neutral

D) Variable

Answer: C) Neutral

Question 8: Which of the following represents the correct electronic configuration of oxygen?

A) 2, 6

B) 2, 8

C) 2, 4

D) 2, 2, 4

Answer: B) 2, 8

Question 9: Who discovered the electron?

A) J.J. Thomson

B) Ernest Rutherford

C) Marie Curie

D) Dmitri Mendeleev

Answer: A) J.J. Thomson

Question 10: The atomic number of an element is determined by the number of:

A) Neutrons

B) Electrons

C) Protons

D) Isotopes

Answer: C) Protons

Structure of Atom Class 9 MCQ with Answers – Advanced Level Questions

Question 1: What characteristic of an element dictates its chemical behavior?

(a) Size of the element

(b) Valency of the element

(c) Molar mass of the element

(d) None of these

Answer: (b) Valency of the element

Question 2: Which statement does not align with the properties of an Isotope?

(a) Some elements’ isotopes are radioactive

(b) Isotopes consist of atoms belonging to the same element.

(c) Isotopes vary in neutron count

(d) Isotopes possess similar chemical properties

Answer: (b) Isotopes are atoms of different elements

Question 3: Between Sulphur (S) with atomic number 16 and Chlorine (Cl) with atomic number 17, which is more chemically reactive?

(a) Chlorine

(b) Sulphur

(c) Both are equally reactive

(d) Can’t say

Answer: (a) Chlorine

More resources for class 9

• NCERT Solutions for Class 9 Maths
• NCERT Solutions for Class 9 Science
• NCERT Solutions for Class 9 Social Science

Question 4: Which element does not demonstrate electrovalency?

(a) Sodium

(b) Calcium

(c) Carbon

(d) Chlorine

Answer: (c) Carbon

Question 5: Which statement about the atom’s structure is incorrect?

i. The majority of an atom’s mass is concentrated in the nucleus

ii. The atom is an indivisible particle

iii. The atom overall is neutral

iv. All atoms are stable in their basic state

Choose the correct option:

(a) (i) and (iii)

(b) only (ii)

(c) (ii) and (iv)

(d) none of these

Answer: (c) (ii) and (iv)

Question 6: Who proposed the concept of fixed energy levels around the nucleus?

(a) Ernest Rutherford

(b) Niels Bohr

(c) J.J. Thomson

(d) None of these

Answer: (b) Niels Bohr

Question 7: What prevents an atom from collapsing?

(a) The nuclear forces

(b) Movement of electrons in discrete energy levels

(c) The electron-electron repulsions

(d) All of these

Answer: (b) Movement of electrons in discrete energy levels

Question 8: Which pair represents isobars?

(a) 17Cl35 & 17Cl37

(b) 18Ar40 & 20Ca40

(c) 6C12 & 6C14

(d) None of these

Answer: (b) 18Ar40 & 20Ca40

Question 9: Which statement is incorrect regarding observations in Rutherford’s α-particle scattering experiment?

(a) Some α-particles rebound after hitting the gold foil

(b) Some particles deflect from their path

(c) Some particles fail to pass through the gold foil

(d) Most particles pass straight through the gold foil

Answer: (a) Some α-particles rebound after hitting the gold foil

Question 10: Which radioactive element is utilized in cancer treatment?

(a) Iodine-131

(b) Uranium-234

(c) Plutonium-239

(d) Cobalt-60

Answer: (d) Cobalt-60

Question 11: Why do most elements seek to participate in chemical combinations?

i. To gain more electrons

ii. To achieve inert gas configuration

iii. To complete their octet

iv. To complete their inner shells

Choose the correct option:

(a) Both (i) & (iii)

(b) Both (ii) & (iii)

(c) Only (ii)

(d) Both (i) & (iv)

Answer: (b) Both (ii) & (iii)