Class 9 · Science · Chemistry

Atoms and MoleculesPractice Questions & MCQs

Practice Atoms and Molecules questions for Class 9 Science - important MCQs and practice questions with answers and step-by-step solutions. Solve the sample Atoms and Molecules questions below, then get the full set free on the RankByte app.

Topics covered

Laws of Chemical Combination (Conservation of Mass, Constant Proportions)Atomic Mass and Molecular MassMole Concept and Avogadro's NumberWriting Chemical FormulaeValency and IonsLaws of Chemical CombinationChemical FormulaeMolecular and Formula MassMole ConceptLaws of chem combination, mole concept, formulae

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Atoms and MoleculesQuiz - Solve & Score

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  1. Q1. Which postulate of Dalton's atomic theory directly explains the law of conservation of mass?

    • A.atoms are neither created nor destroyed in a chemical reaction
    • B.atoms of different elements have different masses
    • C.atoms combine in small whole-number ratios
    • D.atoms are divisible into electrons

    Answer: A. atoms are neither created nor destroyed in a chemical reaction

  2. Q2. Which postulate of Dalton's theory explains the law of constant proportions?

    • A.atoms combine in a fixed, simple whole-number ratio in a given compound
    • B.atoms are neither created nor destroyed
    • C.atoms are indivisible
    • D.all matter is made of atoms

    Answer: A. atoms combine in a fixed, simple whole-number ratio in a given compound

  3. Q3. Which observation would VIOLATE the law of constant proportions if it were ever found true?

    • A.pure water samples with different hydrogen-to-oxygen mass ratios
    • B.all pure water having the same 1:8 H:O ratio
    • C.mass being conserved in a reaction
    • D.excess reactant remaining unreacted

    Answer: A. pure water samples with different hydrogen-to-oxygen mass ratios

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Atoms and Molecules - Frequently asked questions

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Yes. These Atoms and Molecules important questions follow the Science exam pattern (CBSE Boards, plus JEE and NEET foundation), so they help with both school and competitive prep.

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