THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL OF TANZANIA

FORM TWO NATIONAL ASSESSMENT

032 CHEMISTRY

Time: 2:30 Hours Year: 2025

Instructions

1. This paper consists of sections A and B with a total of ten (10) questions.
2. Answer all the questions in the spaces provided.
3. Section A and C carry fifteen (15) marks each and section B carries seventy (70) marks.
4. All writing must be in black or blue ink, except diagrams which must be in pencil.
5. Communication devices and any unauthorized materials are not allowed in the assessment room.
6. Write your Assessment Number at the top right corner of every page

SECTION A (15 Marks)

Answer all questions in this section.

1. For each of the items (i) - (x), choose the correct answer from among the given alternatives and write its letter in the box provided.

(i) The knowledge of chemistry is useful in many fields of study except

1. forestry.
2. agriculture.
3. laundry.
4. political science.

(ii) A Form Two student used a measuring cylinder to prepare oxygen by decomposing H₂O₂. What is the function of the cylinder in this experiment?

1. To measure volume
2. To measure weight
3. To measure width
4. To measure volume length

(iii) Which pairs represents suitable alternative heat sources when the Bunsen burner is not available in the laboratory?

1. Kerosene stove and firewood
2. Torch and spirit burner
3. Firewood and gas stove
4. Gas stove and spirit burner

(iv) In an experiment to determine the solubility of common salt, the amount of water was kept constant. What type of variable does water represent in this experiment?

1. Dependent variable
2. Controlled variable
3. Independent variable
4. Uncontrolled variable

(v) When solid ammonium chloride is heated strongly, it changes to gaseous molecules. Select the type of change related to this process.

1. Melting
2. Sublimation
3. Condensation
4. Freezing

(vi) Why do ships often have blocks of magnesium attached to their hull?

1. To improve appearance of the hull
2. To make the hull more stronger
3. To give sacrificial protection to the hull
4. To make the hull float easily

(vii) Why is wind said to be the promising source of energy for the future?

1. It does not produce harmful gases
2. It is easily stored
3. It is harnessed without chemical reaction
4. It is a renewable source of energy

(viii) Which element corresponds to the electronic structure 2:8:8?

1. Argon
2. Neon
3. Lithium
4. Helium

(ix) Why elements such as boron, silicon, germanium and antimony are referred to as metalloids?

1. They display non-metallic characteristics
2. They form alloys and conduct electricity
3. They display metallic characteristics
4. They display both metallic and non-metallic characteristics

(x) How many electrons are gained by sulphur in forming sulphate ion?

1. 3
2. 6
3. 5
4. 2

2. Match the descriptions in List A with the correct techniques for separating mixtures in List B by writing the letter of the correct response besides the corresponding item number in the table provided.

SECTION B (70 Marks)

Answer all questions in this section.

3. (a) Identify five apparatuses used to prepare hydrogen gas.

(b) How is oxygen gas prepared by using hydrogen peroxide?

4.Describe five laboratory safety measures.

5. (a) What are the applications of combustion in daily life? Give four points.

(b) How is a portable fire extinguisher used? Explain four stages.

6. (a) Identify four findings given by Rutherford about the atomic structure.

(b) Describe three sub atomic particles according to location and charge.

7. (a) Which three elements should be stored in oil?

(b) Why is it recommended not to expose those three elements in (a) in air?

(c) Briefly describe the alkaline earth metals by giving five points.

8. (a) State two chemical properties of water.

(b) Describe the hydrological cycle without using a diagram.

9. (a) Indicate the status of the following chemical species by writing whether they have stable or unstable electronic configurations.

(b) (i) What is the oxidation number of a free element?

(ii) Give the oxidation number of hydrogen in LiH.

(iii) Give the oxidation state of oxygen in F₂O.

(iv) Identify the oxidation state of oxygen in CO₂.

(v) How many atoms are there in three molecules of water?

SECTION C (15 Marks)

Answer question ten (10).

10. (a) Why the water gas is widely used as an industrial fuel?

(b) Why the government of Tanzania discourages the use of charcoal and firewood as fuels? Give two reasons.

(c) Classify the following substances based on their origin.