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Some Basic Concepts of Chemistry ISC Class 11 MCQ & Practice Questions

Practice Some Basic Concepts of Chemistry MCQs for ISC Class 11 Chemistry with answers, explanations, chapter revision and related ChemNexa mock tests.

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Some Basic Concepts of Chemistry Revision Guide for ISC Class 11 Chemistry

Some Basic Concepts of Chemistry is part of ISC Class 11 Chemistry preparation. A strong revision plan should combine concept review with exam-style questions so that definitions, relationships, calculations and exceptions are recalled accurately.

Use the sample MCQs on this page to check understanding, then attempt the related ChemNexa tests for broader practice. When an answer is wrong, review the explanation and return to the underlying concept before attempting another set.

Important Topics

  • Core definitions and principles
  • Important equations or relationships
  • Common applications and examples
  • Frequently confused concepts
  • Exam-style multiple-choice questions
  • Error review and targeted revision

Revision Tip

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What to practise in Some Basic Concepts of Chemistry

Concept Revision

Revise definitions, principles, equations, trends and core ideas from Some Basic Concepts of Chemistry before attempting MCQs.

Exam-style MCQs

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Top 20 Some Basic Concepts of Chemistry MCQs with Answers

These public questions are selected from the exact Some Basic Concepts of Chemistry chapter, screened for topic relevance and deduplicated so repeated versions of the same MCQ are not shown publicly. Use them for quick revision, then sign in to attempt the complete test experience with more questions, results and performance review.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

1. One mole contains how many elementary entities?

  • A. 3.011 × 10^23
  • B. 6.022 × 10^22
  • C. 1.204 × 10^24
  • D. 6.022 × 10^23
Answer: D
Explanation: One mole contains Avogadro's number, approximately 6.022 × 10^23 entities.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

2. The molar mass of CO2 is:

  • A. 28 g mol^-1
  • B. 18 g mol^-1
  • C. 44 g mol^-1
  • D. 32 g mol^-1
Answer: C
Explanation: CO2 has molar mass 12 + 2×16 = 44 g mol^-1.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

3. 18 g of H2O corresponds to:

  • A. 18 mol
  • B. 1 mol
  • C. 0.5 mol
  • D. 2 mol
Answer: B
Explanation: The molar mass of H2O is 18 g mol^-1, hence 18 g is 1 mol.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

4. The law stating that mass is neither created nor destroyed in a chemical reaction is:

  • A. Law of conservation of mass
  • B. Law of multiple proportions
  • C. Avogadro law
  • D. Boyle law
Answer: A
Explanation: Lavoisier's law of conservation of mass requires total mass to remain constant.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

5. A pure compound always contains the same elements in the same mass ratio. This is:

  • A. Law of reciprocal proportions
  • B. Gay-Lussac law
  • C. Charles law
  • D. Law of definite proportions
Answer: D
Explanation: The law of definite proportions states that a compound has fixed composition by mass.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

6. One atomic mass unit is defined as:

  • A. 1/16 of oxygen-16
  • B. Mass of one proton exactly
  • C. 1/12 of the mass of a carbon-12 atom
  • D. Mass of one electron
Answer: C
Explanation: The unified atomic mass unit is one-twelfth of the mass of a carbon-12 atom.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

7. An empirical formula represents:

  • A. Molar volume
  • B. Simplest whole-number ratio of atoms
  • C. Exact number of atoms in every molecule
  • D. Structural arrangement
Answer: B
Explanation: The empirical formula gives the simplest integral ratio of constituent atoms.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

8. If empirical formula mass is 30 and molar mass is 60, the molecular formula multiplier is:

  • A. 2
  • B. 1
  • C. 3
  • D. 4
Answer: A
Explanation: n = molar mass/empirical formula mass = 60/30 = 2.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

9. A limiting reagent is the reactant that:

  • A. Has the highest molar mass
  • B. Is always a gas
  • C. Remains after reaction
  • D. Is consumed first and limits product formation
Answer: D
Explanation: Product formation stops when the limiting reagent is exhausted.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

10. Molarity is defined as:

  • A. Grams per mole
  • B. Moles of solvent per litre
  • C. Moles of solute per litre of solution
  • D. Moles of solute per kg solvent
Answer: C
Explanation: M = moles of solute divided by litres of solution.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

11. Molality is defined as:

  • A. Moles of solvent per mole solute
  • B. Moles of solute per kilogram of solvent
  • C. Moles per litre of solution
  • D. Grams per litre
Answer: B
Explanation: Molality uses kilograms of solvent as the denominator.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

12. Which concentration term is essentially independent of temperature?

  • A. Molality
  • B. Molarity
  • C. Volume percent
  • D. Volume concentration
Answer: A
Explanation: Molality depends on mass, which does not appreciably change with temperature.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

13. The sum of mole fractions of all components of a mixture is:

  • A. 0
  • B. 100
  • C. Avogadro number
  • D. 1
Answer: D
Explanation: Each mole fraction is ni/ntotal, so their sum equals unity.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

14. How many significant figures are present in 0.00450?

  • A. 4
  • B. 5
  • C. 3
  • D. 2
Answer: C
Explanation: Leading zeros are not significant; 4, 5 and the final zero are significant.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

15. Accuracy describes:

  • A. Size of the sample
  • B. Closeness to the accepted value
  • C. Agreement among repeated measurements only
  • D. Number of decimal places only
Answer: B
Explanation: Accuracy measures closeness to a true or accepted value.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

16. Precision describes:

  • A. Agreement among repeated measurements
  • B. Closeness to the true value only
  • C. Correct unit conversion
  • D. Molar mass
Answer: A
Explanation: Precision concerns reproducibility among repeated observations.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

17. Density is:

  • A. Volume divided by mass
  • B. Moles divided by mass
  • C. Mass multiplied by volume
  • D. Mass divided by volume
Answer: D
Explanation: Density = mass/volume.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

18. Percent yield equals:

  • A. Actual + theoretical
  • B. Actual × theoretical
  • C. Actual yield/theoretical yield × 100
  • D. Theoretical/actual × 100
Answer: C
Explanation: Percent yield compares actual product with the stoichiometric maximum.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

19. For 2H2 + O2 -> 2H2O, 2 mol H2 require:

  • A. 4 mol O2
  • B. 1 mol O2
  • C. 2 mol O2
  • D. 0.5 mol O2
Answer: B
Explanation: The balanced equation gives a 2:1 H2:O2 mole ratio.

ISC Class 11 Chemistry · Some Basic Concepts of Chemistry · Very Hard

20. For N2 + 3H2 -> 2NH3, 3 mol H2 can form:

  • A. 2 mol NH3
  • B. 1 mol NH3
  • C. 3 mol NH3
  • D. 6 mol NH3
Answer: A
Explanation: The coefficients give 3 mol H2 to 2 mol NH3.

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Some Basic Concepts of Chemistry Practice Tests

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How should I prepare Some Basic Concepts of Chemistry for ISC Class 11 Chemistry?

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