THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL OF TANZANIA
FORM TWO NATIONAL ASSESSMENT
032 CHEMISTRY
Time: 2:30 HoursYear: 2020
Instructions
1. This paper consists of sections A and B with a total of ten (10) questions.
2. Answer all questions in the spaces provided.
3. Section A carries twenty (20) marks and section B carries eighty (80) marks.
4. All writing must be in black or blue ink except diagrams which must be in pencil.
5. Cellular phones and any unauthorised materials are not allowed in the assessment room.
6. Write your Assessment Number at the top right corner of every page.
7. The following atomic masses may be used: H = 1, N = 14, 0 = 16, S = 32, Ca = 40.
SECTION A (20 Marks)
Answer an questions in this section.
I .For each of the items (1) (x), choose the correct answer from among the given alternatives and write its letter in the box provided.
(i) The net charge inside the nucleus of an atom is contributed by
(ii) Why oxygen as one of the components of air is unique?
(iii) Which material is not involved in respiration?
(iv) Which element causes permanent hardness of water when combined with sulphate?
(v) Carbon dioxide. Oxygen, Nitrogen and Hydrogen Sulphide are
(vi) Which common feature is associated with elements of the same group?
(vii) The oxidation state of metallic elements is always
(viii) An isotope of Lead with atomic number of 82 and mass number of 207 has
(ix) Which conditions are necessary for iron nails to rust?
(x) Which decision should be made if the results of an experiment do not support the stated hypothesis?
7. (a)Why is petrol not recommended to be used as fuel in school laboratories? Briefly explain.
View Ans(b) Which three heat sources can be used to boil some water in the laboratory instead of the Bunsen burner?
View Ans(c) Arrange the following steps for lighting the Bunsen burner in a correct sequence using letter
A to F.
Answer
Step | 1 | 2 | 3 | 4 | 5 | 6 |
Letter |
8. (a)Giving a reason, state whether rust will form or not in each of the situations (i) - (vi).
(b)Briefly explain any four methods of preventing rusting.
View Ans9(a)Write chemical formulae of the two compounds from which oxygen gas can be prepared by decomposition.
View Ans(b)What are the three physical properties of oxygen gas?
View Ans(c) Why is it important to have abundant oxygen gas on the Earth? Give five reasons.
View Ans10. Identify the five accidents which are common in the laboratory and in each explain possible causes and preventive measures to be taken.
View AnsTHE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL OF TANZANIA
FORM TWO NATIONAL ASSESSMENT
032 CHEMISTRY
Time: 2:30 HoursYear: 2020
Instructions
1. This paper consists of sections A and B with a total of ten (10) questions.
2. Answer all questions in the spaces provided.
3. Section A carries twenty (20) marks and section B carries eighty (80) marks.
4. All writing must be in black or blue ink except diagrams which must be in pencil.
5. Cellular phones and any unauthorised materials are not allowed in the assessment room.
6. Write your Assessment Number at the top right corner of every page.
7. The following atomic masses may be used: H = 1, N = 14, 0 = 16, S = 32, Ca = 40.
SECTION A (20 Marks)
Answer an questions in this section.
I .For each of the items (1) (x), choose the correct answer from among the given alternatives and write its letter in the box provided.
(i) The net charge inside the nucleus of an atom is contributed by
(ii) Why oxygen as one of the components of air is unique?
(iii) Which material is not involved in respiration?
(iv) Which element causes permanent hardness of water when combined with sulphate?
(v) Carbon dioxide. Oxygen, Nitrogen and Hydrogen Sulphide are
(vi) Which common feature is associated with elements of the same group?
(vii) The oxidation state of metallic elements is always
(viii) An isotope of Lead with atomic number of 82 and mass number of 207 has
(ix) Which conditions are necessary for iron nails to rust?
(x) Which decision should be made if the results of an experiment do not support the stated hypothesis?
2. (a)Match each item in List A with a correct response in List B by writing the letter of the correct response below the corresponding item number in the table provided.
List A | List B |
(i) An element with atomic number (ii) The type of bonding which occurs between non metals. (iii) Elements in the Periodic Table found in groups IV to VII. (iv) Vertical columns of the Periodic Table. (v) Elements which react vigorously with water |
|
(b) Answer the given questions by writing the correct answer in the blank spaces provided.
(i) In which stage is the hypothesis tested during scientific investigation? . . . . . . . . . . . . . . . . .
(ii) On which factor does the physical state of a molecule depend? . . . . . . . . . . . . . . . . .
(iii) Which properties depend on the proportions of mixing substances in a mixture? . . . . . . . . . . . . . . . . .
(iv) What are the building blocks of matter? . . . . . . . . . . . . . . . . .
(v) Which particles are transferred during chemical reactions? . . . . . . . . . . . . . . . . .
View Ans
SECTION B (80 Marks)
Answer all questions in this section.
3. (a) Why candles are not suitable for heating in the laboratory? Give two reasons.
View Ans(b) Differentiate luminous from non-luminous flame by giving five points.
View Ans4. (a) State four main ideas of the Dalton's atomic theory of matter.
View Ans(b)Classify each of the following elements into their respective groups and periods.
SIN | Element | Group | Period |
(i) | Calcium |
|
|
(ii) | Hydrogen |
|
|
(iii) | Chlorine |
|
|
(iv) | Boron |
|
|
(v) | Aluminium |
|
|
5. (a)With an example for each, give two fields in which the scientific procedure is applied.
View Ans(b) Categorize the three factors (variables) which affect the problem being investigated during scientific investigation.
View Ans6, (a) Briefly explain why:
(i) the use of charcoal is harmful to the environment.
(ii)charcoal is still being used by majority of Tanzanians for domestic purposes.
View Ans(b) A mass of 20.0 g of petrol was burnt in air. The heat produced was used to heat 2.5 litres of water. Given that the heat value of petrol is 43,640 kJ/kg, by how much the temperature of water could have changed? (The specific heat capacity of water = 4.18 Id kg-1 K-1, Density of water = 1000 kg/m3).
View Ans7. (a)Why is petrol not recommended to be used as fuel in school laboratories? Briefly explain.
View Ans(b) Which three heat sources can be used to boil some water in the laboratory instead of the Bunsen burner?
View Ans(c) Arrange the following steps for lighting the Bunsen burner in a correct sequence using letter
A to F.
8. (a)Giving a reason, state whether rust will form or not in each of the situations (i) - (vi).
(b)Briefly explain any four methods of preventing rusting.
View Ans9(a)Write chemical formulae of the two compounds from which oxygen gas can be prepared by decomposition.
View Ans(b)What are the three physical properties of oxygen gas?
View Ans(c) Why is it important to have abundant oxygen gas on the Earth? Give five reasons.
View Ans10. Identify the five accidents which are common in the laboratory and in each explain possible causes and preventive measures to be taken.
View Ans