Pok Oi Hospital Tang Pui King Memorial College

1st Term Test ( 1996-1997 )

F.4    Chemistry

Class                      :               ________________                           Date                  :    ______________

Name                      :               ________________                           Time allowed   :     60 mins

Class No.               :               ________________                           ( P.1 - P.4/38 )

Instructions to students:

The total score of this paper is 100 marks.

Answer all questions.

Answer Section A and Section B in the foolscap papers provided.

Section A  (40%)

1. If a student spilt some concentrated nitric acid on his fingers in laboratory, he should at once

    A. wash his finger with dil. NH₄OH solution.

    B. switch on the tap water to wash his fingers.

    C. dry his fingers with a filter paper and wash them with tap water.

    D. cover his fingers with a piece of wet cloth.

2. From the symbol He, it can be deduced that

    A. an atom of helium has two protons and four neutrons in its nucleus.

    B. an atom of helium contains two electrons.

    C. helium occurs as a diatomic molecule.

    D. helium has an atomic number of 4.

3. Which of the following is NOT a chemical change?

    A. Making bread by mixing water, flour, baking powder and putting the mixture in an

         oven.

    B. Lighting a cigarette.

    C. Taking in anti- acid tablets.

    D. Making ice cubes by freezing water.

4. Change of states is best explained by

    A. diffusion.

    B. Brownian Movement.

    C. the Particle Theory of Matter.

    D. the Kinetic Theory of Matter

5. Strontium is below calcium in the Periodic Table. Which of the following statements

    about strontium is/are correct?

          (1) It is a non- metal.

          (2) It reacts with cold water.

          (3) It has two outermost shell electrons.

    A. (3) only

    B. (1) and (2) only

    C. (2) and (3) only

    D. (1),(2) and (3)

6. Elements X and Y react to form an ionic compound with the formula X₂Y. Element Y

    and hydrogen react to form a covalent compound with the formula YH₂. To which

    Group does X belong?

    A. I

    B. II

    C. VI

    D. VII

7. The Rutherford’s scattering experiment helped to establish the atomic theory by

    demonstrating that

    A. the atom have a large empty space with a concentrated positive charge.

    B. the atom is a solid sphere with a concentrated positive charge.

    C. the atom is a hollow sphere with negative charges on the spherical surface.

    D. the atom is a hollow sphere with positive charges on the spherical surface.

8. The element X with an atomic number of 7 forms a diatomic molecule, X₂. The

    bonding in its diatomic molecule, X₂ is expected to be

    A. ionic.

    B. single covalent.

    C. double covalent.

    D triple covalent.

9. Which of the following ions is/are coloured?

           (1) MnO₄^- (aq)

           (2) Cr₂O₇^2- (aq)

           (3) Fe²⁺ (aq)

    A. (1) and(2) only

    B. (1) and (3) only

    C. (2) and (3) only

    D. (1), (2) and (3)

10 Lead (II) bromide can conduct electricity in the molten state but not in the solid state

     because

    A. solid lead (II) bromide consists of molecules.

    B. solid lead (II) bromide does not consist of ions.

    C. molten lead (II) bromide consists of freely moving electrons.

    D. molten lead (II) bromide consists of mobile ions.

Section B  (60%)

1. The compositions of five particles: A, B, C, D and E are given below.

 (a) What is the atomic number of B?

 (b) What is the mass number of B?

 (c) Draw the electronic configuration of E.

 (d) What are isotopes?

     Which two of the above particles are isotopes?

 (e) Which of the above particles is/are ion(s)? Label it/ them with positively charged or

     negatively charged ion.

(f) Which particles belong to the same group in the Periodic Table?

                                                                                                (10 marks)

 2.

(a) Use the information in the table above to answer the following questions. Give the

      name of the element whose atom

      (I)    has an electronic arrangement 2,7.

      (II)   has an octet structure.

      (III)  has extra- stability.

      (IV)  forms a cation (positive ion) by losing one electron.

      (V)   forms an anion (negative ion) by gaining two electrons.

(b) Draw the electronic diagram for magnesium fluoride (showing the outermost shell

      electrons only).

(c) Name the element whose atomic number is 19 and deduce its electronic arrangement.

                                                                                                       (10 marks)

3. The following is a list of symbols for some elements.

    Al, Au Cl, Fe, H, He, Hg, Ne, Si

(a) Which of them is/are metal(s)?

 (b) Give three properties of metals.

(c) Which of them is/are non-metal(s)?

(d) Which of them is/are noble gas(es)?

(e) Which of them is/are semi-metal(s)?

                                                                                        (10 marks)

  4.

Answer the following questions with the symbol given in the Periodic Table shown above.

(a) Which element is the most reactive metal?

 (b) Which element is the most reactive non-metal?

 (c) Which element is found as monoatomic gas in nature?

 (d) List all possible elements which can conduct current.

 (e) What is the group name of

     (I)    elements B and F,

     (II)   elements J and L,

(III)            elements C and K.                                                            (10 marks)

5.(a) Chlorine is made up of two isotopes.

Isotope                           % in nature

                                    75%  

                                     25%

        (I)    What is meant by “ relative atomic mass” ?

        (II)   Calculate the relative atomic mass of chlorine.

    (b) An element has three isotopes ²⁰X, ²¹X and ²²X. the ratio of abundance of ²⁰X

          and ²²X is 2 to 1. The relative atomic mass of X is 20.86. Find the percentage

          composition of isotopes of X.

(10 marks) 

6. A small crystal of potassium permanganate was placed in the middle of a strip of filter paper. The paper had been moistened with sodium sulphate solution. After the circuit was closed, purple patch slowly moved as shown in the diagram.

(a) What was the purpose of moistening the filter paper with sodium sulphate solution

      before the experiment?

 (b)    (I)    Which ion was responsible for the purple patch?

        (II)   Which electrode (P or Q) was positive pole?

 (c)    (I)    Towards which electrode (P or Q) were potassium ions migrating? Why?

        (II)   Could you see the movement of potassium ions? Why?

 (d) If the above experiment had proceeded for some time and the positive and negative

   poles were then reversed, state what would happen and explain briefly.

                                                                                      (10 marks)

 End of paper