Class 11 Chemistry MCQ Chapter 1 Some Basic Concepts of Chemistry
Are you looking for Class 11 Chemistry MCQ Chapter 1 Some Basic Concepts of Chemistry English Medium? Then you have come to the right place. This article provides important multiple-choice questions (MCQs) with answers for AHSEC Higher Secondary First Year students to help them prepare effectively for examinations.
The chapter Some Basic Concepts of Chemistry is the foundation of Chemistry and introduces students to important topics such as matter, laws of chemical combination, atomic and molecular masses, mole concept, molar mass, percentage composition, empirical formula, molecular formula, and stoichiometry. A clear understanding of these concepts is essential for studying advanced Chemistry chapters.
The MCQs included in this article are based on the latest AHSEC syllabus and examination pattern. These objective questions will help students revise important topics, strengthen their problem-solving skills, and improve their confidence before examinations.
Whether you are preparing for class tests, annual examinations, or the AHSEC HS First Year Examination, these MCQ questions and answers will support your Chemistry preparation and help you score better marks.
Part: I
Some Basic Concepts of Chemistry
Selected VSA & MCQ
I. Very Short Answer Questions (VSA)
Q What is chemistry?
Ans: Chemistry is the branch of science that studies matter, its properties, composition, and changes.
Q What is matter?
Ans: Matter is anything that has mass and occupies space.
Q Define atomic mass.
Ans: Atomic mass is the mass of an atom expressed in atomic mass units (amu).
Q Define molar mass.
Ans: The mass of one mole of a substance expressed in grams.
Q What is empirical formula?
Ans: The simplest whole-number ratio of atoms in a compound.
Q What is molecular formula?
Ans: The actual number of atoms of each element in a molecule.
Q State the law of conservation of mass.
Ans: Mass is neither created nor destroyed in a chemical reaction.
Q State the law of definite proportions.
Ans: A compound always contains elements in a fixed ratio by mass.
Q What is stoichiometry?
Ans: The calculation of quantities in chemical reactions.
Q Define limiting reagent.
Ans: The reactant that gets completely consumed first.
Q What is percentage composition?
Ans: Percentage of each element in a compound by mass.
Q Define significant figures.
Ans: Digits that carry meaningful precision in measurements.
Q What is dimensional analysis?
Ans: A method to convert units using conversion factors.
Q What is atomic number?
Ans: Number of protons in the nucleus.
Q What is molecular mass?
Ans: Sum of atomic masses of atoms in a molecule.
Q What is concentration?
Ans: Amount of solute present in a given amount of solution.
Q Define molarity.
Ans: Moles of solute per litre of solution.
Q What is ppm?
Ans: Parts per million, a unit of concentration.
Q What is balanced equation?
Ans: Equation with equal number of atoms on both sides.
Q What is oxidation?
Ans: Loss of electrons or increase in oxidation state.
Q What is reduction?
Ans: Gain of electrons or decrease in oxidation state.
Q What is a chemical reaction?
Ans: Process where substances change into new substances.
Q Define reactants.
Ans: Substances that take part in a reaction.
Q Define products.
Ans: Substances formed in a reaction.
Q What is gram atomic mass?
Ans: Atomic mass expressed in grams.
Q What is gram molecular mass?
Ans: Molecular mass expressed in grams.
Q What is ideal solution?
Ans: Solution that obeys Raoult’s law.
Q What is mass percentage?
Ans: Mass of solute per 100 g of solution
I. Multiple Choice Questions (MCQs)
Q What is the SI unit of amount of substance?
(a) gram
(b) mole
(c) kilogram
(d) litre
Ans: (b) mole
Q Law of conservation of mass was given by:
(a) Dalton
(b) Lavoisier
(c) Proust
(d) Rutherford
Ans: (b)
Q Empirical formula represents:
(a) actual atoms
(b) simplest ratio
(c) molecular weight
(d) structure
Ans: (b)
Q Limiting reagent is:
(a) excess reactant
(b) catalyst
(c) fully consumed reactant
(d) solvent
Ans: (c)
Q Molarity depends on:
(a) volume
(b) temperature
(c) mass
(d) pressure
Ans: (b)
Q Percentage composition is calculated using:
(a) mole ratio
(b) mass ratio
(c) volume ratio
(d) density
Ans: (b)
Q Balanced equation obeys:
(a) Dalton law
(b) conservation law
(c) gas law
(d) Boyle law
Ans: (b)
Q Stoichiometry deals with:
(a) structure
(b) quantitative relation
(c) bonding
(d) energy
Ans: (b)
Q Significant figures indicate:
(a) accuracy
(b) precision
(c) errors
(d) units
Ans: (b)
Q Molecular formula is multiple of:
(a) empirical formula
(b) atomic formula
(c) mass formula
(d) ionic formula
Ans: (a)
Q Molar mass unit is:
(a) g
(b) g/mol
(c) mol/g
(d) kg
Ans: (b)
Q ppm stands for:
(a) parts per mole
(b) parts per million
(c) pressure per mole
(d) none
Ans: (b)
Q Law of definite proportions was given by:
(a) Dalton
(b) Lavoisier
(c) Proust
(d) Thomson
Ans: (c)
Q Oxidation involves:
(a) gain of electrons
(b) loss of electrons
(c) no change
(d) gain of neutrons
Ans: (b
Q Reduction involves:
(a) loss of electrons
(b) gain of electrons
(c) loss of protons
(d) gain of neutrons
Ans: (b)
Q Atomic number equals:
(a) neutrons
(b) protons
(c) electrons + neutrons
(d) mass
Ans: (b)
Q Molarity unit is:
(a) mol/L
(b) g/L
(c) mol/g
(d) L/mol
Ans: (a)
Q Gram molecular mass equals:
(a) molecular mass in grams
(b) atomic mass
(c) density
(d) volume
Ans: (a)
Q Dimensional analysis is used for:
(a) structure
(b) unit conversion
(c) bonding
(d) reaction
Ans: (b)
Q Reactants are:
(a) products
(b) starting materials
(c) catalysts
(d) solvents
Ans: (b)
Q Products are:
(a) starting materials
(b) final substances
(c) catalysts
(d) solvents
Ans: (b)
Q Concentration is:
(a) volume
(b) mass
(c) solute amount
(d) solute per solution
Ans: (d)
Q Mass percentage formula uses:
(a) volume
(b) density
(c) mass
(d) pressure
Ans: (c)
Q Balanced equation has:
(a) equal atoms
(b) equal molecules
(c) equal masses
(d) equal volumes
Ans: (a)
Q Empirical formula of glucose is:
(a) CH₂O
(b) C₆H₁₂O₆
(c) CO₂
(d) H₂O
Ans: (a)
Q Molecular mass is:
(a) sum of masses
(b) difference
(c) ratio
(d) product
Ans: (a)
Q Assertion: Matter has mass and occupies space.
Reason: Matter is made up of atoms.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (a)
Q Assertion: Law of conservation of mass is always valid.
Reason: Mass can be created in chemical reactions.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (c)
Q Assertion: Empirical formula gives simplest ratio.
Reason: Molecular formula gives actual number of atoms.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (b)
Q Assertion: Limiting reagent determines product amount.
Reason: It is completely consumed in reaction.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (a)
Q Assertion: Molarity changes with temperature.
Reason: Volume changes with temperature.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (a)
Q Assertion: Significant figures indicate precision.
Reason: More digits mean more accuracy always.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (c)
Q Assertion: Balanced equation obeys conservation law.
Reason: Number of atoms remains same.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (a)
