O-Level Chemistry Model Question-06

Chemistry

Time : 2 hrs.                                                                                                                                     Marks. 40

Answer five questions of each group.

Group - A

1.         What is law of constant proportions ? Explain with example.                                                        2

2.         What is radical ? Give example.                                                                                                      2

3.         What are isobar and isotope ? Give example.                                                                                             2

4.         What kind of compound is MgCl₂ ? Justify.                                                                                               2

5.         What is the effect of Temperature on chemical reaction ?                                                              2

6.         According to La-chatelier's principle explain the effect of pressure on the following reaction.     2

            N₂ (g) + 3H₂ (g) « 2NH₃ (g) + 92.5 kjmol ^-1.

7.         Why are metals are good conductors of electricity ?                                                                                  2

8.         Why ionic compounds have high melting point ?                                                                           2

9.         Write down the limitations of Bohr's atom model.                                                                         2

10.       State Avogadro's law with an example.                                                                                          2

Group - B

11.       a)         Define variable valency, active valency and dormant valency with example.                    3

            b)         Explain law of reciprocal proportions with example.                                                                      3

12.       a)         What are fundamental particles ? Describe the stable fundamental particles.                     3

            b)         State the characteristics of modern periodic table.                                                              3

13.       a)         Describe Rutherfoor's atom model with limitations.                                                                       3

            b)         State the properties of covalent and ionic compounds.                                                       3

           

14.       a)         Show how the size of atoms of element changes in a group and in a period.                     3

            b)         What are the factors which affect a chemical reaction ?                                                     3

15.       a)         What is the effect of concentration on chemical reaction ? Explain with example.                        3

                                                                                                                                                                    1+2=3

            b)         State the Le-chatelier's principle. Describe the effect of Temperature on the following reaction.

                        2 SO₂ (g) + O₂ (g)  «  2SO₃ (g) + 192.5 kj.            

16.       a)         What is catalyst ? Describe different types of catalysts.                                                     3

b)        Explain the order of reactivity of the elements of the group II a by showing their reactions with water.

           

17.       a)         Describe the limitations of modern periodic table.                                                              3

            b)         Write down the differences between empirical formula and molecular formula.               3

18.       a)         Determine the position of the following elements in the periodic table.                             3

                        i)          K         ii)         P          iii)        Mg

            b)         Draw the structure of the following mollecules.                                                                 3

                        i)          CH₄                 ii)         NH₃                iii)        H₂O

19.       a)         What is valency ? Explain with two examples.                                                                   3

b)        A compound has C=85.71% and H = 14.29%. It's vapour density is 28, find the motecnlar formula of that compound.

20.       a)         Prove that the molecular mass of any gas is twice it's vapour density.                               3

            b)         Write down the rules of writing chemical equations.                                                          3