O-level Chemistry Sample Question-15

[ N.B. The figures in the margin indicate full marks. Answer any five questions form group A and group B each.]

Group A

1.         How would you detect Cu²⁺ ion, explain with equation?                                                               2

2.         Write the formulae of   (i)  white vitriol   (ii)  lead sugar.                                                               2

3.         What would you mean by passivation of iron?                                                                               2

4.         How would you detect  Fe ²⁺ and Fe ³⁺ ion in solution?                                                                 2

5.         How would you detect sulphide and sulphate ions in samples?                                                     2

6.         What is meant by functional groups? Write down the functional groups of alcohol and esters.    2

7.         What happens when fats react with sodium hydroxide?                                                                2

8.         Define catalyst and catalysis.                                                                                                                      2

9.         What do you mean by molar Mass and molecular mass?                                                                2

10.       What is the mass of a molecule of nitrogen?

Group -B

11.       a)         How can a reversible reaction be made to go in one direction?                                          2

            b)         Explain the mechanism of electrolysis?                                                                               3

            c)         What do you mean by reactivity series? Write the order of reactivity of the elements.      1

12.       a)         Define heat of neutralization? Why is the heat of neutralization of strong acids by                      3

            strong bases constant?                                                                                                                                

            b)         Explain how is steel manufactured from cast iron.                                                              3

13.       a)         Explain how green vitriol is prepared? What is the use of it?                                             2+1

            b)         Potash alum is a double salt. Justify your answer.                                                               3

14.       a)         CO₂ is a gas whereas Si O₂ is a high melting point solid, explain why this happen?                      2

            b)         Describe the extraction process of Aluminum.                                                                    3

            c)         What do you mean by equilibrium constant?                                                                                  1

15.       Write what happen when______.                                                                                        1x4=6

            i)          Ethanol reacts with ethanoic acid.

            ii)         Propene reacts with Br₂.

            iii)        Ammonium carbonate is heated.

            iv)        Hexanoic acid is burnt is air or O₂.

           

16.       a)         What is a covalent bond? Explain with example how covalent bond is formed.                3

            b)         Find the position of the element in the periodic table, which has atomic number 16. If

            this element gain two electrons, then mention the total electron number.                                      2

            c)         What is Avogadro number?                                                                                                 1

17.       a)         A compound has C= 85.71%, and H= 14.29%. Its vapour density is 28. Find the molecular

            formula of the compound.                                                                                                               3

            b)         Explain bohr's Atom model.                                                                                                2

            c)         What is difference between H₂ O and CO₂ molecule?                                                        1

18.       a)         Explain with examples of polymerisation and Isomerisation reactions.                              3

            b)         State the faraday's Laws of electrolysis.                                                                             2

            c)         What is electroplating?                                                                                                        1

19.       a)         State the law of Multiple proportions.                                                                                 2

            b)         Carbon disulphide contains 15.79% sulphur and cardon-di- oxide contains 27.27%

            carbon. Show that the above data supports the law of Reciprocal proportions.                             3

            c)         Write down the qualitative significance of H₂ SO₄.                                                                        1

20.       a)         Write four differences of metals and non-metals.                                                               2

            b)         What do you mean by on isotope? Explain with examples.                                                            2

            c)         What is sublimation. Give an example.                                                                                2