CBSE Class 9 Chemistry Structure of the Atom MCQs Set 17

Download CBSE MCQs for Class 9 Chemistry: Structure of the Atom

Review structured MCQ sets for Class 9 Chemistry Structure of the Atom. Built according to official CBSE guidelines, these downloadable questions support daily revision and core concept reinforcement.

Chapter-wise Objective Questions: Structure of the Atom

View or download the dedicated Structure of the Atom MCQ resource below. Practicing these 50 objective questions regularly builds familiarity with standard exam patterns and helps secure higher marks in final Chemistry evaluations.

Multiple Choice Questions

Question 1: Which pair are isobars?
(a) deuterium and tritium
(b) radium and radon
(c) sodium-23 and magnesium-24
(d) argon-40 and calcium-40
Show Answer & Explanation

Answer: (d) argon-40 and calcium-40

Explanation:
1. Isobars have the same mass number but different atomic numbers.
2. Argon (Z = 18) and calcium (Z = 20) both can have mass number 40.

Teacher's Note:
1. Same A, different Z.

Question 2: The atomic masses of most elements are fractional because
(a) elements contain isotopes in a definite ratio
(b) their determination is difficult
(c) of impurities
(d) the standard is faulty
Show Answer & Explanation

Answer: (a) elements contain isotopes in a definite ratio

Explanation:
1. Atomic mass is the average of the masses of the natural isotopes weighted by their abundance.

Teacher's Note:
1. Average of isotopes.

Question 3: Which statement is false?
(a) The mass of an atom is concentrated in its nucleus
(b) The number of neutrons in an atom equals its atomic number
(c) Gamma rays have no charge
(d) The first shell holds a maximum of two electrons
Show Answer & Explanation

Answer: (b) The number of neutrons in an atom equals its atomic number

Explanation:
1. Neutrons are not always equal to protons; for example, uranium-238 has 146 neutrons and atomic number 92.

Teacher's Note:
1. Check with an example.

Question 4: Alpha particles are identical with
(a) X-rays
(b) electrons
(c) helium nuclei
(d) neutrons
Show Answer & Explanation

Answer: (c) helium nuclei

Explanation:
1. An alpha particle is \( ^4_2He^{2+} \): two protons and two neutrons.

Teacher's Note:
1. Charge +2, mass 4 u.

Question 5: Among neutron, proton, electron and alpha particle, the lightest is the
(a) neutron
(b) proton
(c) alpha particle
(d) electron
Show Answer & Explanation

Answer: (d) electron

Explanation:
1. Electron mass is about \( \frac1{1836} \) of the proton mass.

Teacher's Note:
1. Electron mass is tiny.

Question 6: Which of the following is a radioactive element?
(a) thorium
(b) zinc
(c) mercury
(d) copper
Show Answer & Explanation

Answer: (a) thorium

Explanation:
1. Elements with atomic number above 82 are radioactive; thorium has Z = 90.

Teacher's Note:
1. Heavy nuclei are unstable.

Question 7: The accurate atomic masses of isotopes were determined by
(a) J. J. Thomson using a cathode ray tube
(b) F. W. Aston using the mass spectrograph
(c) Faraday using electrolysis
(d) Soddy using chemical analysis
Show Answer & Explanation

Answer: (b) F. W. Aston using the mass spectrograph

Explanation:
1. Aston built the mass spectrograph which separates ions of different mass and measures their masses.

Teacher's Note:
1. Mass spectrograph.

Question 8: The discovery that was an accidental one is that of
(a) the neutron
(b) the electron
(c) radioactivity (Becquerel)
(d) the proton
Show Answer & Explanation

Answer: (c) radioactivity (Becquerel)

Explanation:
1. Becquerel found that uranium salts fogged a wrapped photographic plate without being exposed to light.

Teacher's Note:
1. Chance observation.

Free study material for Science

Structure of the Atom Objective Questions & Solutions for Class 9 Chemistry

Chapter MCQs with Answers for Class 9 Chemistry

Review structured objective questions for Class 9 Chemistry Structure of the Atom. Built according to official CBSE guidelines, these MCQ sets support daily revision and core concept reinforcement.

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FAQs

Where can I access latest CBSE Class 9 Chemistry Structure of the Atom MCQs Set 17?

You can get most exhaustive CBSE Class 9 Chemistry Structure of the Atom MCQs Set 17 for free on StudiesToday.com. These MCQs for Class 9 Chemistry are updated for the 2026-27 academic session as per CBSE examination standards.

Are Assertion-Reasoning and Case-Study MCQs included in the Chemistry Class 9 material?

Yes, our CBSE Class 9 Chemistry Structure of the Atom MCQs Set 17 include the latest type of questions, such as Assertion-Reasoning and Case-based MCQs. 50% of the CBSE paper is now competency-based.

How do practicing Chemistry MCQs help in scoring full marks in Class 9 exams?

By solving our CBSE Class 9 Chemistry Structure of the Atom MCQs Set 17, Class 9 students can improve their accuracy and speed which is important as objective questions provide a chance to secure 100% marks in the Chemistry.

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Yes, Chemistry MCQs for Class 9 have answer key and brief explanations to help students understand logic behind the correct option as its important for 2026 competency-focused CBSE exams.

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