1. The formation of SO2 and SO3 explain A. the law of conservation of mass B. the law of multiple proportions C. the law of definite properties D. Boyle’s law Ans: B
2. One gram of which of the following contains largest number of oxygen atoms? A. O B. O2 C. O3 D. All contains same Ans: C
3. The law of definite proportions was given by – A. John Dalton B. Humphry Davy C. Proust D. Michael Faraday Ans: C
4. Molecular mass is defined as the A. mass of one atom compared with the mass of one molecule B. mass of one atom compared with the mass of one atom of hydrogen C. mass of one molecule of any substance compared with the mass of one atom of C-12 D. None of these Ans: C
5. The chemical symbol for barium is A. B B. Ba C. Be D. Bi Ans: B
6. A group of atoms chemically bonded together is a (an) A. molecule B. ion C. salt D. element Ans: A
7. Adding electrons to an atom will result in a (an) A. molecule B. anion C. cation D. salt Ans: B
8. When an atom loses electrons, it is called a (an) _____ and has a ______ charge. A. anion, positive B. cation, positive C. anion, negative D. cation, positive Ans: B
9. The molecular formula P2O5 means that A. a molecule contains 2 atoms of P and 5 atoms of O B. the ratio of the mass of P to the mass of O in the molecule is 2:5 C. there are twice as many P atoms in the molecule as there are O atoms D. the ratio of the mass of P to the mass of O in the molecule is 5 : 2 Ans: A
10. The percentage of copper and oxygen in samples of CuO obtained by different methods were found to be the same. The illustrate the law of A. constant proportions B. conservation of mass C. multiple proportions D. reciprocal proportions Ans: A
11. The total number of atoms represented by the compound CuSO₄.5H₂O is A. 27 B. 21 C. 5 D. 8 Ans: B
12. The correct symbol for silver is A. Ag B. Si C. Ar D.Al Ans: A
13. The cathode ray experiment was done for the first time by A. J.J. Thomson B. John Dalton C. Goldstein D. Rutherford Ans: A
14. The nucleus of an atom contains A. protons B. electrons C. protons and neutrons D. neutrons Ans: C
15. By whom was neutron discovered? A. Bohr B. Chadwick C. Rutherford D. Dalton Ans: B
16. In an atom valence electron are present in A. outermost orbit B. next to outermost orbit C. first orbit D. any one of its orbit Ans: A
17. Which of the following statements is incorrect for cathode rays? A. They move in straight line B. Their nature depends upon the nature of gas present in the discharge tube. C. They cost shadow of solid objects placed in their path D. They get deflected towards positive charge. Ans: B
18. The isotopes of an element have A. same number of neutrons B. same atomic number C.same mass number D. None of these Ans: B
19. Which of the following pairs are isotopes? A. Oxygen and ozone B. Ice and steam C. Nitric oxide and nitrogen dioxide D. Hydrogen and deuterium Ans: D
20. Which of the following have equal number of neutrons and protons? A. Hydrogen B. Deuterium C. Fluorine D. Chlorine Ans: B
21. The number of electrons in an element with atomic number X and atomic mass Y will be A. (X – Y) B. (Y – X) C. (X + Y) D. X Ans: D
22. Which of the following has a charge of +1 and a mass of 1 amu ? A. A neutron B. A proton C. An electron D. A helium nucleus Ans: B
23. Which of the following describes an isotope with a mass number of 99 that contains 56 neutrons in its nucleus ? A. [latex]{^{99}_{56}Ba}[/latex] B. [latex]{^{43}_{56}Ba}[/latex] C. [latex]{^{99}_{43}Tc}[/latex] D. [latex]{^{56}_{43}Tc}[/latex] Ans: C
24. Which of the following isotopes is used as the standard for atomic mass ? A. [latex]{{12}_c}[/latex] B. [latex]{{16}_O}[/latex] C. [latex]{{13}_c}[/latex] D. [latex]{{13}_c}[/latex] Ans: A
25. Which of the following is not a basic particle of an element? A. An atom B. A molecule C. An ion D. None of these Ans: B
26. Members of which of the following have similar chemical properties ? A. Isotope B. Isobars C. Allotropes D. Both isotopes and allotropes Ans: C
27. While performing cathode ray experiments, it was observed that there was no passage of electric current under normal conditions. Which of the following can account for this observation ? A. Dust particles are present in air B. Carbon dioxide is present in air C. Air is a poor conductor of electricity under normal conditions D. None of these Ans: C
28. Which one of the following statement is not true ? A. Most of the space in an atom is empty B. The total number of neutrons and protons is always equal in a neutral atom C. The total number of electrons and protons in an atom is always equal D. The total number of electrons in any energy level can be calculated by the formula [latex]2n^2[/latex] Ans: B
29. Dalton's atomic theory successfully explained (i) Law of conservation of mass (ii) Law of constant composition (iii) Law of radioactivity (iv) Law of multiple proportion A. (i), (ii) and (iii) B. (i), (iii) and (iv) C. (ii), (iii) and (iv) D. (i), (ii) and (iv) Ans: D
30. Which one of the following laws explains the formation of carbon monoxide and carbon dioxide from carbon and oxygen? A. Law of conservation of mass B. Law of multiple proportions C. Law of reciprocal proportions D. Law of definite proportions Ans: B
31. The atomic weights are expressed in terms of atomic mass unit. Which one of the following is used as a standard? A. [latex]{1}_{H_1}[/latex] B. [latex]{12}_{C_6}[/latex] C. [latex]{16}_{O_8}[/latex] D. [latex]{35}_{Cl_17}[/latex] Ans: B
32. Which would be the electrical charge on a sulphur atom containing 18 electrons ? A. 2– B. 1– C. 0 D. 2+ Ans: A
33. The atomic number of an element is 11 and its mass number is 23. The correct order representing the number of electrons, protons and neutrons respectively in this atom is A. 11, 11, 12 B. 11, 12, 11 C. 12, 11, 11 D. 23, 11, 23. Ans: A
34. In an atom valence electron are present in A. outermost orbit B. next to outermost orbit C. first orbit D. any one of its orbit Ans: A
35. In a chemical change the total weight of the reacting substances compared to total weight of products is A. never the same B. always less C. always more D. always the same Ans: D