1 Which of the following statements about isotopes is correct? A They have different chemical properties. B They have the same mass number. C They have the same atomic number but different mass numbers. D They have the same number of neutrons.
2 Which of the following correctly represents the atomic number (Z) and mass number (A) of an atom? A Z = number of neutrons, A = number of protons B Z = number of protons, A = number of protons + neutrons C Z = number of electrons, A = number of protons + electrons D Z = number of nucleons, A = number of protons
3 Which isotope is used in the treatment of cancer? A Carbon-14 B Cobalt-60 C Uranium-235 D Iodine-131
4 Which of the following isotopes is used in the treatment of cancer? A Cobalt-60 B Carbon-14 C Uranium-235 D Iodine-131
5 The maximum number of electrons that can be accommodated in the L shell (n=2) is: A 2 B 8 C 18 D 32
6 Which of the following is NOT a postulate of Bohr's atomic model? A Electrons revolve in fixed orbits. B Energy is emitted or absorbed when electrons jump between orbits. C Electrons can revolve in any orbit. D Each orbit has a fixed energy.
7 In Rutherford's gold foil experiment, most alpha particles passed straight through the foil because: A The atom is mostly empty space B The nucleus is positively charged C Electrons are embedded in a positive sphere D Alpha particles are neutral
8 How many electrons are present in the outermost shell of a chlorine atom (atomic number 17)? A 1 B 2 C 7 D 8
9 An atom of carbon-14 contains: A 6 protons, 8 neutrons, 6 electrons B 6 protons, 6 neutrons, 8 electrons C 8 protons, 6 neutrons, 6 electrons D 6 protons, 6 neutrons, 6 electrons
12 The mass number of an atom is the sum of: A Protons and electrons B Electrons and neutrons C Protons and neutrons D Protons, neutrons and electrons
13 In Bohr's atomic model, electrons revolve around the nucleus in: A Random paths B Fixed energy levels C Straight lines D Elliptical orbits
14 The atomic number of an element is determined by the number of: A Neutrons B Protons C Electrons D Nucleons
15 In the periodic table, elements are arranged in order of increasing: A Mass number B Atomic number C Number of neutrons D Atomic mass
16 How many electrons can the third shell (M shell) hold according to the Bohr-Bury scheme? A 2 B 8 C 18 D 32
18 According to Bohr's model, when an electron jumps from a higher orbit to a lower orbit: A Energy is absorbed B Energy is released C No energy change occurs D The electron escapes from the atom
19 Which subatomic particle was discovered by J.J. Thomson using cathode ray tube experiments? A Proton B Neutron C Electron D Nucleus
21 According to Bohr's model, electrons revolve around the nucleus in: A Random paths B Fixed energy levels C The nucleus D Straight lines
24 The atomic number of an element is 17. What is the element? A Fluorine B Chlorine C Bromine D Iodine