Chemistry Grade 9 Multiple Choice Quiz

1. Which of the following best defines chemistry?

a) The study of living organisms and their environments. b) The science that deals with the properties, composition, and structure of substances, the transformations they undergo, and the energy released or absorbed during these processes. c) The branch of science concerned with the nature and properties of matter and energy, excluding transformations. d) The study of ancient Greek philosophies about matter.

2. Why is chemistry often called the 'central science'?

a) Because it is the oldest branch of science. b) Because it primarily deals with the center of the Earth. c) Because it links various fields of natural science like biology, physics, and geology, all of which involve 'stuff'. d) Because it focuses on the properties of central elements in the periodic table.

3. Which of the following is NOT an SI base unit?

a) Meter (m) b) Kilogram (kg) c) Liter (L) d) Kelvin (K)

4. In the SI system, what is the correct abbreviation for "degrees Kelvin"?

a) °K b) K c) Kelv d) °Kelvin

5. Which type of uncertainty can be reduced but never completely eliminated?

a) Systematic uncertainties b) Calibration errors c) Random uncertainties d) Inaccurate meter sticks

6. According to the rules for significant figures in addition and subtraction, the answer cannot have:

a) More significant figures than the number with the fewest significant figures. b) More digits to the right of the decimal point than any of the original numbers. c) Fewer digits to the right of the decimal point than any of the original numbers. d) Fewer significant figures than the number with the most significant figures.

7. The Greek philosopher Empedocles thought that all materials are made up of four things called elements. What were they?

a) Gold, Silver, Water, Soap b) Protons, Neutrons, Electrons, Nucleus c) Earth, Air, Water, and Fire d) Hydrogen, Oxygen, Carbon, Nitrogen

8. The word 'atom' is derived from a Greek word 'a-tomos' which means:

a) Indivisible b) Divisible c) Visible d) Transparent

9. Who formulated the Law of Conservation of Mass, stating that mass is neither created nor destroyed in chemical reactions?

a) Joseph Louis Proust b) John Dalton c) Antoine Lavoisier d) J.J. Thomson

10. The Law of Definite Proportions states that:

a) The ratios of masses of elements in a compound are small whole numbers. b) Mass is neither created nor destroyed in chemical reactions. c) The masses of elements in a compound always occur in varying proportions. d) Every chemical compound contains fixed and constant proportions (by mass) of its constituent elements.

11. What was one of the drawbacks of Dalton's Atomic Theory that was later proved wrong?

a) Elements are made of small particles called atoms. b) Atoms combine in small whole numbers to form compounds. c) The indivisibility of an atom was proved wrong, as atoms can be subdivided into protons, neutrons, and electrons. d) All atoms of the same element have the same atomic number.

12. Who discovered the electron in 1897 through experiments with cathode rays?

a) Eugene Goldstein b) Ernest Rutherford c) J.J. Thomson d) Robert Millikan

13. In J.J. Thomson's 'plum pudding' model of the atom, where were the electrons located?

a) In a central nucleus surrounded by a positive charge. b) Revolving around a central nucleus in fixed orbits. c) Embedded in a uniform sphere of positive charge like blueberries stuck into a muffin. d) Delocalized in a sea of positive ions.

14. What key observation from Rutherford's gold foil experiment contradicted Thomson's model of the atom?

a) All alpha particles passed straight through the gold foil. b) Alpha particles were deflected at large angles, and some were reflected directly back at the source. c) The gold foil became negatively charged. d) The alpha particles gained electrons from the gold foil.

15. According to Bohr's Atomic Model, what is true about electrons?

a) Electrons revolve around the nucleus in fixed, concentric circular orbits. b) Electrons can spiral into the nucleus if they lose energy. c) Electrons are randomly dispersed around the nucleus. d) Electrons have a continuous range of energies.

16. Who discovered the neutron in 1932?

a) Eugene Goldstein b) Ernest Rutherford c) Niels Bohr d) James Chadwick

17. What is the approximate mass of an electron compared to a proton or neutron?

a) About 2000 times larger. b) About 1/2000 the mass of a proton or neutron. c) Identical to the mass of a proton. d) Negligible, so it doesn't contribute to atomic mass.

18. What defines the atomic number (Z) of an atom?

a) The total number of protons and neutrons in its nucleus. b) The total number of electrons in its outermost shell. c) The number of protons in its nucleus. d) The average mass of its isotopes.

19. Atoms of the same element that differ in their numbers of neutrons are called:

a) Isobars b) Allotropes c) Isotopes d) Ions

20. What was the basis for Mendeleev's initial classification of elements in the periodic table?

a) Increasing atomic number. b) Similar chemical properties. c) Increasing atomic weights. d) Electronic configuration.

21. The modern periodic law states that the physical and chemical properties of the elements are periodic functions of their:

a) Atomic weights. b) Atomic mass units. c) Atomic number. d) Number of valence electrons.

22. As you move from left to right across a period in the modern periodic table, the atomic radius generally:

a) Increases. b) Decreases. c) Stays the same. d) First increases then decreases.

23. Ionization energy is the energy required for an isolated, gaseous atom to:

a) Gain an electron. b) Lose an electron. c) Form a chemical bond. d) Become electrically neutral.

24. Which of the following elements is the most electronegative according to the Linus Pauling scale?

a) Cesium (Cs) b) Fluorine (F) c) Chlorine (Cl) d) Hydrogen (H)

25. What is the octet rule?

a) Atoms always aim to have two valence electrons. b) Atoms tend to form compounds in ways that give them eight valence electrons to achieve stability. c) Atoms in a compound always share electrons equally. d) Noble gases are unstable because they have eight valence electrons.

26. An ionic bond is typically formed between:

a) Two non-metallic elements. b) Two metallic elements. c) A metallic element and a non-metallic element. d) Atoms with a very small electronegativity difference.

27. Which of the following is a general property of ionic compounds?

a) Low melting and boiling points. b) Poor conductors of electricity in molten state. c) Brittle nature. d) Soluble in non-polar solvents.

28. A covalent bond is formed when two atoms:

a) Transfer one or more electron pairs. b) Exchange electrons to form ions. c) Share one or more electron pairs. d) Have a large electronegativity difference.

29. In a nonpolar covalent bond, the shared pair of electrons is:

a) Unevenly distributed between the two atoms. b) Transferred completely from one atom to another. c) Equally attracted by the two atoms. d) Provided by only one of the bonded atoms.

30. Which of the following describes a coordinate covalent bond (dative bond)?

a) An electron pair is transferred from one atom to another. b) An electron pair is shared equally between two atoms. c) The electron pair is provided by only one of the bonded atoms but shared by both atoms after bond formation. d) It is formed between oppositely charged ions.

31. What is a key characteristic of metallic bonding?

a) Electrons are tightly bound to individual atoms. b) Electrons are transferred from metals to non-metals. c) Electrons are said to be delocalized, moving freely throughout the structure. d) It only forms between different metallic atoms.