Class 9 Science Chapter 3 Atoms and Molecules MCQ with Solutions

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Atoms and Molecules is one of the fundamental chapters in Class 9 Science, and practicing Multiple Choice Questions (MCQs) can be an effective way to prepare for the exam. Students following the CBSE Class 9 Science syllabus can use these Atoms and Molecules MCQs to test their knowledge and boost their exam performance. These MCQs are designed to cover important concepts from Chapter 3 of the CBSE Class 9 Science curriculum.

In this article, you will find easy, moderate, and difficult-level questions, along with their answers, to help students fully grasp the essential concepts of Atoms and Molecules. Moreover, we recommend referring to NCERT Solutions Class 9 Science and CBSE Notes Class 9 for a deeper understanding.

Class 9 Science MCQs – Chapter-wise

Atoms and Molecules Class 9 MCQs

Atoms and Molecules Class 9 MCQ

These MCQs are designed to challenge students and help them assess their understanding of key topics from the Atoms and Molecules chapter. The questions range from simple factual queries to more complex application-based ones, reflecting the type of questions commonly asked in the CBSE Class 9 Science exam.

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Class 9 Science Atoms and Molecules MCQs (Easy Level)

Here are eight very short and Easy Level multiple-choice questions (MCQs) along with their answers for CBSE Class 9 Science chapter “Atoms and Molecules”:

Q1. Which of the following is NOT a subatomic particle?

a) Neutron

b) Proton

c) Electron

d) Ion

Answer: d) Ion

Q2. What is the smallest particle of an element that retains its properties?

a) Atom

b) Molecule

c) Ion

d) Neutron

Answer: a) Atom

Q3. Who proposed the plum pudding model of an atom?

a) J.J. Thomson

b) Ernest Rutherford

c) Niels Bohr

d) James Chadwick

Answer: a) J.J. Thomson

Q4. The atomic number of an element is determined by the number of:

a) Protons

b) Electrons

c) Neutrons

d) Nucleons

Answer: a) Protons

Q5. Which of the following is NOT a compound?

a) Water (H2O)

b) Oxygen (O2)

c) Carbon dioxide (CO2)

d) Hydrochloric acid (HCl)

Answer: b) Oxygen (O2)

Q6. The mass number of atom is equal to total number of:

a) Protons and neutrons

b) Protons and electrons

c) Neutrons and electrons

d) Electrons only

Answer: a) Protons and neutrons

Q7. Who proposed the planetary model of an atom?

a) J.J. Thomson

b) Ernest Rutherford

c) Niels Bohr

d) James Chadwick

Answer: c) Niels Bohr

Q8. Which of the following is NOT a chemical reaction?

a) Rusting of iron

b) Burning of magnesium

c) Dissolving sugar in water

d) Melting of ice

Answer: d) Melting of ice

Q9. Which scientist’s experiment led to the discovery of the nucleus of an atom?

a) J.J. Thomson

b) Ernest Rutherford

c) Niels Bohr

d) Dmitri Mendeleev

Answer: b) Ernest Rutherford

Class 9 Important Links
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Atoms and Molecules Class 9 Science MCQ (Moderate Level)

Q1. Which of the following statements best describes an atom?

a) Atoms are the smallest particles of matter that can exist independently.

b) Atoms are composed of protons and electrons only.

c) Atoms cannot be broken down further by chemical means.

d) Atoms of different elements have the same mass number.

Answer: a) Atoms are the smallest particles of matter that can exist independently.

Q2. What is the significance of the atomic number of an element?

a) It represents the number of protons in the nucleus of an atom.

b) It indicates the number of electrons in the outermost shell of an atom.

c) It determines the mass of the atom.

d) It reflects the number of neutrons in the nucleus.

Answer: a) It represents the number of protons in the nucleus of an atom.

Q3. Which model of the atom states that electrons are distributed in various energy levels or shells?

a) Rutherford’s model

b) Bohr’s model

c) Dalton’s model

d) Thomson’s model

Answer: b) Bohr’s model

Q4. What is the term used to describe atoms of the same element having different numbers of neutrons?

a) Isotopes

b) Ions

c) Molecules

d) Compounds

Answer: a) Isotopes

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Q5. Which subatomic particle has negligible mass?

a) Proton

b) Electron

c) Neutron

d) Nucleus

Answer: b) Electron

Q6. The mass of an atom is mainly attributed to the combined masses of its components.

a) Protons and neutrons

b) Protons and electrons

c) Neutrons and electrons

d) Protons, neutrons, and electrons

Answer: a) Protons and neutrons

Q7. What is the charge of an alpha particle?

a) Positive

b) Negative

c) Neutral

d) Variable

Answer: a) Positive

Q8. Which of the following represents a molecular formula?

a) H

b) O2

c) NaCl

d) Fe

Answer: b) O2

Also Check: NCERT Book Class 9 Science

Chapter 3 Chemistry Class 9 Atoms and Molecules MCQs (Difficult Level)

Here are 10 difficult level multiple choice questions (MCQs) on the topic of “Atoms and Molecules” for Class 9 Science Chapter 3

Q1. Which of the following particles has the least mass?

a) Proton

b) Neutron

c) Electron

d) Positron

Answer: c) Electron

Q2. The number of molecules present in one mole of any substance is

a) 6.022 × 10²³

b) 6.002 × 10²³

c) 6.022 × 10²²

d) 6.002 × 10²²

Answer: a) 6.022 × 10²³

Q3. What is the mass of one atom of carbon-12 in grams?

a) 12 g

b) 1 g

c) 1/12 g

d) 6 g

Answer: c) 1/12 g

Q4. The formula unit mass of a compound is:

a) Molecular mass × Avogadro’s number

b) Molecular mass × Molar mass

c) Molecular mass × 1/Avogadro’s number

d) Molar mass × 1/Avogadro’s number

Answer: d) Molar mass × 1/Avogadro’s number

Q5. The empirical formula of a compound is CH₂ and its molecular mass is 56. The molecular formula will be:

a) C₂H₄

b) C₄H₈

c) C₃H₆

d) C₅H₁₀

Answer: b) C₄H₈

Q6. Which of the following is NOT a diatomic molecule?

a) Oxygen (O₂)

b) Nitrogen (N₂)

c) Hydrogen (H₂)

d) Carbon dioxide (CO₂)

Answer: d) Carbon dioxide (CO₂)

Q7. The number of atoms present in 11.5 grams of sodium is approximately:

a) 6.022 × 10²³

b) 3.011 × 10²³

c) 1.806 × 10²⁴

d)3.706 × 10²⁴

Answer: c) 1.806 × 10^24

Q8. Which of the following contains the maximum number of molecules?

(a) 19 CO2

(b) 1 g N2

(d) 1 g CH4

Answer: (c) 1 g H2

Q9. A sample of NH3 molecule, irrespective of source, contains 82.35% Nitrogen and 17.65% of Hydrogen by mass. This data supports:

(a) Law of Conservation of Mass

(b) Law of Multiple Proportions

(d) Avogadro’s Law

Answer: (c) Law of Definite Proportions

Q10. An element X has a valency of 2, while another element Y has a valency of 4. What compound will form when these two elements combine?

(a) XY

(b) XY2

(d) XY4

Answer: (b) XY2

Q11. The molecular formula of potassium nitrate is ________.

(a) KNO3

(b) KNO

(d) KON

Answer: (a) KNO3

Q12. 3.42 g of sucrose are dissolved in 18 g of water in a beaker. The number of oxygen atoms present are:

(a) 6.68 × 10²³

(b) 6.09 × 10²²

(d) 6.022 × 10²¹

Answer: (a) 6.68 × 10²³

Q13. The number of atoms in one mole of a substance is:

a) 6.022 × 10²³

b) 3.011 × 10²³

c) 1.806 × 10²⁴

d)3.706 × 10²⁴

Answer: a) 6.022 × 10²³

Q14. The mass of one mole of a substance is equal to its:

a) Atomic mass

b) Molecular mass

c) Formula unit mass

d) Molar mass

Answer: d) Molar mass

Why Practice Atoms and Molecules MCQs?

Practicing Atoms and Molecules MCQs regularly helps Class 9 students to:

Improve their understanding of key concepts like atomic structure, atomic number, isotopes, and the structure of molecules.
Enhance problem-solving skills required for solving more complex questions during exams.
Get familiar with the types of questions that are commonly asked in CBSE Class 9 Science exams, helping them manage time effectively.

Class 9 Science MCQs Preparation: Resources

Along with the MCQs, we recommend exploring additional resources to further strengthen your preparation:

NCERT Solutions Class 9 Science for comprehensive explanations of every topic in Atoms and Molecules.
CBSE Notes Class 9 that provide a detailed overview of each chapter.
NCERT Exemplar Solutions Class 9 for advanced practice questions and examples.

Conclusion

The Atoms and Molecules chapter in Class 9 Science lays the foundation for many advanced topics in chemistry. Mastering the concepts through regular practice of MCQs not only prepares students for their school exams but also builds a strong base for future topics in science. To excel in the exams, ensure regular practice, study from multiple sources, and refer to NCERT solutions for in-depth understanding.

For more practice and resources, visit Infinity Learn for study materials, worksheets, and expert guidance to help you prepare for the CBSE Class 9 Science exam.