POK OI HOSPITAL TANG PUI KING MEMORIAL COLLEGE

POK OI HOSPITAL TANG PUI KING MEMORIAL COLLEGE

FIRST TERM TEST ( 1997-1998 )

S4 CHEMISTRY

Class : ________________ Date : __________________

Name : ________________ Time allowed: 60 minutes

Class Number : ________________ ( P.1 - P.4 /53 )

Instructions to students:

1. Answer ALL questions.

2. Write your answers on the foolscap papers provided.

3. The total score is 100 marks.

________________________________________________________________________

Section A :Multiple Choice Questions ( 40 % )

1. Concentrated sulphuric acid causes severe burns. If it happens that some concentrated sulphuric acid is

splashed into the eyes, one should wash with plenty of

A. tetrachloromethane.

B. sodium carbonate solution..

C. sodium hydroxide solution.

D. water.

2. Which of the following is/are TRUE description(s) of metals?

(1) They are usually shiny in appearance.

(2) They are good conductors of heat and electricity.

(3) They are low in melting and boiling points

A. (1) and (2) only.

B. (1) and (3) only.

C. (2) and (3) only.

D. All of the above.

3. Which of the following about an atom of the element is correct?

Number of protons Number of neutrons Number of electrons

A. 19 18 19

B. 37 19 19

C. 18 19 18

D. 19 37 37

4. A cation X³⁺has 18 electrons. How many protons does an atom X contain?

A. 15

B. 18

C. 21

D. None of the above

5. Two particles have the following compositions.

23 protons, 30 neutrons, 21 electrons.

22 protons, 30 neutrons, 21 electrons.

They would best be described as

A. metallic element.

B. positive ions.

C. isotopes.

D. atoms of non-metals.

6.Rubidium is an alkali metal. Whish of the following statements concerning it is/are CORRECT?

(1) It reacts with water to give hydrogen.

(2) It is soft.

(3) It reacts with water to form an acidic solution.

(4) It is less reactive than sodium.

A. (1) only

B. (1) and (2) only.

C. (3) and (4) only.

D. (2), (3) and (4) only.

7. The atomic number of an element E is 17. The atomic number of another element with chemical properties similar to those of E is

A. 9.

B. 16.

C. 18.

D. 20.

8. Which of the following statements about iron(II)sulphide is TRUE?

A. It is not attracted by magnet.

B. It separates into two layers with addition of the water.

C. It is a yellowish black solid.

D. It gives hydrogen when reacting with dilute hydrochloric acid.

9. Elements X and Y react to form a gaseous product with a chemical formula XY₂.

If Y belongs to group VI of the Periodic Table, to which group does X belong?

A. group II

B. group IV

C. group VI

D. Group VII

10.

In the above diagram, which of the following crystals would result in colour moving

towards the positive electrode?

Cobalt (II) chloride
Lead (II) sulphate
Potassium permanganate
Sodium chloride.

Section B : Questions ( 60 % )

1. (a) A student prepared some chemicals in the laboratory. What safety precaution should be taken

(1) if she performed the experiment involving some poisonous gas?

(2) If she heated some mixtures that might cause harm to eyes?

(3) If she handled a very flammable substance?

(4) If she was not using the Bunsen burner for a while?

(5) If she was a girl with long hair?

(5marks)

(b) The following chemicals (A-D) are labeled with different hazard warning labels.

Suggest the dangerous nature of each chemical.

(5 marks)

2. Thallium (symbol T1) is a metal that occurs naturally a mixture of two isotopes.

The relative abundance of the isotopes is shown in the table below.

Isotope	A	B
Mass number of isotope	203	204
Abundance (%)	29.52	70.48

(a) What is meant by the term ‘isotope’?

(b) Calculate the relative atomic mass of thallium. (Correct your answer to 2 decimal places.)

(d) Thallium forms the compound thallium sulphate, Tl₂SO₄.

(1) What is the change on the thallium ion?

(2) What is the formula of thallium nitrate?

(10 masks)

3. Complete the table.

Name	Formula	Name	Formula
(a)	ZnO	Ammonium nitrate	(f)
(b)	PbBr₂	Potassium sulphate	(g)
(c)	CaSO₄	Copper (II) oxide	(h)
(d)	NaNO₃	Magnesium hydroxide	(i)
(e)	CuCl₂	Aluminium chloride	(j)

(10 marks)

4. The table below lists some physical properties of lead, bromine and lead(II) bromide.

Substance	Lead	Bromine	Lead(II) bromide
Melting point	328°C	-7°C	370°C
Electrical conductivity in the solid state	Conducting	Non-conducting	Non-conducting
Electrical conductivity in the liquid state	Conducting	Non-conducting	______

(a) Which of the substances is a compound?

(b) Which of the substances is metallic element?

(d) Explain the difference in melting points between bromine and lead(II) bromide.

(e) Explain the difference in electrical conductivity between lead and lead(II) bromide in solid state.

(f) Will lead(II) bromide conduct electricity in the liquid state? Explain your answer.

(g) Bromine cannot conduct electricity both in solid and liquid states. Why?

(10 marks)

5. Referring to the part of the Periodic Table given below, answer the following questions.

(a) Of the elements in Group I, which one is the most reactive?

(b) Of the elements in Group VII, which one is the most reactive?

(1) Group I elements.

(2) Group II elements.

(3) Group VII elements.

(d) Name the element which is a semi-metal.

(e) With respect to their electronic configuration, what do elements have in common

(1) in the same period?

(2) In the same group?

(f) Draw the electronic configuration of magnesium chloride, showing electrons in the outermost shells only.

(g) Explain briefly why elements in Group 0 seldom from compounds with other elements.

(12 marks)

6. “Ionic compounds are made up of metals and non-metals while covalent compounds are made up of non-metals only.”

Describe how ionic compounds and covalent compounds are formed. In your answer, you should give suitable examples and the electronic structures of the products formed.

(8 marks)

(You are required to give paragraph-length answer to this question. 3 out of the marks will be awarded for the effective communication of knowledge in Chemistry.)

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