SSC CGL MCQ Practice 2026

Chemistry - Atoms & Molecules Questions for SSC CGL (with Answers)

10 Chemistry - Atoms & Molecules MCQs from the General Awareness section, with answers and short explanations.

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Q1. What is the molar mass of water (H2O)? (H = 1, O = 16)

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Answer: B. 18 g/mol

2(1) + 16 = 18, so the molar mass of water is 18 g/mol.

Chemistry - Atoms & Molecules · easy · Beginner Practice Set 3

Q2. The value of Avogadro's number is approximately:

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Answer: D. 6.022 x 10^23

One mole of any substance contains about 6.022 x 10^23 particles.

Chemistry - Atoms & Molecules · easy · Beginner Practice Set 5

Q3. What is the chemical formula of calcium chloride?

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Answer: C. CaCl2

Calcium (valency 2) combines with two chlorine atoms (valency 1) to form CaCl2.

Chemistry - Atoms & Molecules · easy · Beginner Practice Set 7

Q4. What is the chemical symbol of potassium?

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Answer: D. K

Potassium's symbol K comes from its Latin name kalium.

Chemistry - Atoms & Molecules · easy · Beginner Practice Set 9

Q5. What is the chemical formula of aluminium oxide?

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Answer: A. Al2O3

Crossing the valencies Al(3) and O(2) gives Al2O3.

Chemistry - Atoms & Molecules · medium · Intermediate Practice Set 4

Q6. How many atoms in total are present in one molecule of sulphuric acid (H2SO4)?

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Answer: B. 7

H2SO4 has 2 H + 1 S + 4 O = 7 atoms.

Chemistry - Atoms & Molecules · medium · Intermediate Practice Set 7

Q7. How many moles are present in 22 g of carbon dioxide? (C = 12, O = 16)

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Answer: A. 0.5 mol

Molar mass of CO2 = 44 g/mol, so 22 / 44 = 0.5 mol.

Chemistry - Atoms & Molecules · medium · Intermediate Practice Set 7

Q8. Who stated the law of conservation of mass?

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Answer: B. Antoine Lavoisier

Lavoisier established that mass is neither created nor destroyed in a chemical reaction.

Chemistry - Atoms & Molecules · medium · Intermediate Practice Set 8

Q9. What is the mass of 0.5 mole of nitrogen gas (N2)? (N = 14)

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Answer: B. 14 g

Molar mass of N2 = 28 g/mol; 0.5 x 28 = 14 g.

Chemistry - Atoms & Molecules · hard · Advanced Practice Set 4

Q10. One atomic mass unit (u) is defined as:

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Answer: D. 1/12th of the mass of one carbon-12 atom

IUPAC defines 1 u as exactly one-twelfth of the mass of a carbon-12 atom.

Chemistry - Atoms & Molecules · hard · Advanced Practice Set 7

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