Chemistry 9 Short Questions and Answers

Short Questions Answers

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Chemistry 9 Short Questions and Answers – Chapters 1 to 8

Chemistry is a fascinating subject that explores the composition, properties, and transformations of matter. For students in the 9th grade, understanding chemistry fundamentals is crucial for building a strong foundation in science. Below are short questions and answers from important chapters in chemistry.

Chapter 1: Nature of Science in Chemistry

Short Questions and Answers

  1. What is chemistry?
    Chemistry is the branch of science that studies matter’s composition, properties, and changes.

  2. What is the scientific method?
    The scientific method is a systematic approach used in scientific research, including observation, hypothesis, experiment, and conclusion.

  3. Why is chemistry called a central science?
    Chemistry is called a central science because it connects physics and biology, helping us understand different natural processes.

  4. What is a hypothesis?
    A hypothesis is a tentative explanation for an observation that can be tested through experiments.

  5. Define law and theory in chemistry.

    • A law is a statement that describes a consistent natural phenomenon.

    • A theory is a well-tested explanation of observations and experimental results.

  6. What is the difference between qualitative and quantitative observations?

    • Qualitative observations describe properties without numbers (e.g., color, smell).

    • Quantitative observations involve numerical measurements (e.g., mass, temperature).

  7. Who is the father of modern chemistry?
    Antoine Lavoisier is known as the father of modern chemistry.

  8. What is an experiment in chemistry?
    An experiment is a controlled procedure to test a hypothesis.

  9. What is an inference?
    An inference is a conclusion drawn based on observations and previous knowledge.

  10. How does chemistry benefit society?
    Chemistry helps in medicine, agriculture, energy production, and environmental protection.

Chapter 2: Matter

Short Questions and Answers

  1. What is the matter?
    Matter is anything that has mass and occupies space.

  2. What are the three states of matter?
    The three states of matter are solid, liquid, and gas.

  3. What is a physical change?
    A physical change is a change in the form of matter without altering its composition (e.g., melting ice).

  4. What is a chemical change?
    A chemical change is a change in which a new substance is formed (e.g., burning wood).

  5. Define element, compound, and mixture.

    • Element: A pure substance made of one type of atom.

    • Compound: A substance made of two or more different elements chemically combined.

    • Mixture: A combination of two or more substances that are not chemically bonded.

  6. What is the difference between homogeneous and heterogeneous mixtures?

    • Homogeneous mixtures have a uniform composition (e.g., saltwater).

    • Heterogeneous mixtures have a non-uniform composition (e.g., sand and water).

  7. What are atoms and molecules?

    • Atoms are the smallest units of an element.

    • Molecules are groups of two or more atoms bonded together.

  8. What is the law of conservation of mass?
    Mass is neither created nor destroyed in a chemical reaction.

  9. What is the difference between a pure substance and a mixture?

    • A pure substance has a fixed composition (e.g., oxygen gas).

    • A mixture contains two or more substances mixed (e.g., air).

  10. What is plasma?
    Plasma is a high-energy state of matter where atoms lose their electrons.

Chapter 3: Atomic Structure

Short Questions and Answers

  1. What is an atom?
    An atom is the smallest unit of an element that retains its properties.

  2. What are subatomic particles?
    Atoms consist of protons, neutrons, and electrons.

  3. Who discovered the electron?
    J.J. Thomson discovered the electron.

  4. What is the charge of a neutron?
    Neutrons have no charge (neutral).

  5. What is the atomic number?
    The atomic number is the number of protons in an atom.

  6. What is the mass number?
    The mass number is the sum of protons and neutrons in an atom.

  7. What are isotopes?
    Isotopes are atoms of the same element with different numbers of neutrons.

  8. Who proposed the planetary model of the atom?
    Niels Bohr proposed the planetary model of the atom.

  9. What is an ion?
    An ion is a charged atom or molecule.

  10. What is the difference between a cation and an anion?

  • A cation is a positively charged ion (loses electrons).

  • An anion is a negatively charged ion (gains electrons).

Chapter 4: Periodic Table and Periodicity of Properties

Short Questions and Answers

  1. Who created the modern periodic table?
    Dmitri Mendeleev developed the periodic table.

  2. What is a period in the periodic table?
    A period is a horizontal row of elements.

  3. What is a group in the periodic table?
    A group is a vertical column of elements with similar properties.

  4. What are noble gases?
    Noble gases are elements in Group 18, known for their lack of reactivity.

  5. Why do elements in the same group have similar properties?
    They have the same number of valence electrons.

Chapter 5: Chemical Bonding

Short Questions and Answers

  1. What is a chemical bond?
    A chemical bond is the force holding atoms together in a compound.

  2. What are the three main types of chemical bonds?

    • Ionic bond

    • Covalent bond

    • Metallic bond

  3. What is an ionic bond?
    An ionic bond is formed by the transfer of electrons between atoms.

Chapter 6: Stoichiometry

Short Questions and Answers

  1. What is stoichiometry?
    Stoichiometry is the study of quantitative relationships in chemical reactions.

  2. What is a mole in chemistry?
    A mole is a unit representing 6.022×1023 particles.

Chapter 7: Electrochemistry

Short Questions and Answers

  1. What is electrochemistry?
    Electrochemistry is the study of chemical reactions that involve electricity.

  2. What is an electrolyte?
    An electrolyte is a substance that conducts electricity when dissolved in water.

Chapter 8: Energetics

Short Questions and Answers

  1. What is energetics?
    Energetics is the study of energy changes in chemical reactions.

  2. What is an exothermic reaction?
    An exothermic reaction releases energy.