1. Fill in the blanks
(a) In a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is called ————.
(b) A group of atoms carrying a fixed charge on them is called ————.
(c) The formula unit mass of Ca3 (PO4)2 is --------------------
(d) Formula of sodium carbonate is ———— and that of ammonium sulphate is ——
2. Compute the difference in masses of 103 moles each of magnesium atoms and magnesium ions.
(Mass of an electron = 9.1×10–31 kg)
4. Compute the number of ions present in 5.85 g of sodium chloride.
5. A gold sample contains 90% of gold and the rest copper. How many atoms of gold are present in one gram of this sample of gold?
6. What are ionic and molecular compounds? Give examples.
7. Compute the difference in masses of one mole each of aluminum atoms and one mole of its ions. (Mass of an electron is (9.1×10–28 g). which one is heavier?
8. A silver ornament of mass ‘m’ gram is polished with gold equivalent to 1% of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.
9. A sample of ethane (C2H6) gas has the same mass as 1.5 ×1020
10. What is the fraction of the mass of water due to neutrons?
11. Does the solubility of a substance change with temperature? Explain with the help of an example.
12. Calculate the number of moles of magnesium present in a magnesium ribbon weighing 12 g. Molar atomic mass of magnesium is 24g mol-1
13. Verify by calculating that
(a) 5 moles of CO2 and 5 moles of H2O do not have the same mass.
(b) 240 g of calcium and 240 g magnesium elements have a mole ratio of 3:5.
14. A sample of vitamin C is known to contain 2.58 ×1024 oxygen atoms. How many moles of oxygen atoms are present in the sample?
15. The visible universe is estimated to contain 1022 stars. How many moles of stars are present in the visible universe?
16. Compare the properties of electrons, protons and neutrons.
17. What are the limitations of J.J. Thomson’s model of the atom?
18. What are the limitations of Rutherford’s model of atom?
19. Describe Bohr’s model of atom.
20. Compare all the proposed models of an atom given in this chapter.
21. Summarize the rules for writing of distribution of electrons in various shells for the first eighteen elements.
22. Define valency by taking examples of silicon and oxygen
23. Explain with examples (i) Atomic number, (ii) Mass number, (iii) Isotopes and (iv) Isobars. Give any two uses of isotopes.
24. Na+ has completely filled K and L shells. Explain.
25. If bromine atom is available in the form of, say, two isotopes 7935Br (49.7%) and 8135Br (50.3%), calculate the average atomic mass of bromine atom.
YOU MUST VISIT THIS USE FULL LINKNumerical based on mole concept
Related post to 9th Atoms and Molecules