FORM FOUR CHEMISTRY NECTA 2019

THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL OF TANZANIA

CERTIFICATE OF SECONDARY EDUCATION EXAMINATION

032/1 CHEMISTRY 1

(For Both School and Private Candidates)

Time: 3 Hours Thursday, 07th November 2019 a.m.

Instructions

  1. This paper consists of sections A, B and C with a total of fourteen (14) questions.
  2. Answer all questions in sections A and B and one (1) question from section C.
  3. Cellular phones and any unauthorised materials are not allowed in the examination room.
  4. Write your Examination Number on every page of your answer booklet(s).
  5. The following constants may be used.

Atomic masses: H 1, O- 16, N- 14, S = 32, Zn - 65, Cl -35.5, cu - 64.

Avogadros number= 6.02 x 1023

GMV at s.t.p =22.4 dm3 .

1 Faraday= 96,500 coulombs.

Standard pressure = 760 mm Hg. Standard temperature 273 K.

1 litre =1 dm3 =1000 cm 3.

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 beside the item number in the answer booklet provided.

(i) "Water is referred to as the universal solvent". What does this mean?

  1. Water is neither acidic nor basic as compared to other liquids.
  2. Water exists in three states of matter than any other liquids.
  3. Water dissolves both organic and inorganic solutes.
  4. Water is used more domestically than any other liquids.
  5. Water dissolves more substances than any other known liquids.
Choose Answer :


(ii) When methane undergoes substitutional reaction with excess chlorine, what is the final product?

  1. Chloromethane
  2. Dichloromethane 
  3. Trichloromethane 
  4. Tetrachloromethane 
  5. Monochloromethane
Choose Answer :


(iii)  Why is hydrogen gas collected over water and by upward delivery method?

  1. It is insoluble in water and less denser than air.
  2. It is soluble in water and denser than air.
  3. It is insoluble in water and denser than air.
  4. It is soluble in water and less denser than air.
  5. It is soluble in both water and air.
Choose Answer :


(iv) Consider the following fuels which are used for different purposes:

  1. Coal
  2. Fire wood
  3. Petrol
  4. Charcoal.

Which fuels originate from fossils?

  1. 1 and 3
  2. 1 and 4
  3. 2 and 4
  4. 2 and 3
  5. 1 and 2
Choose Answer :


(v) The following are the uses of chromatography except:

  1. to analyse blood in crime scenes.
  2. to detect different fibres.
  3. to detect water pollution.
  4. to bleach dye/colour.
  5. to test purity of organic substances.
Choose Answer :


(vi)  What is the proper set of apparatus would you use to grind granules of a solid substance into fine powder in the laboratory?

  1. Pestle and filter funnel   
  2. Separating funnel and mortar
  3. Pestle and filter paper                  
  4. Pestle and mortar
  5. Thistle funnel and mortar
Choose Answer :


(vii) Oxygen gas can be produced in a large scale by:

  1. condensation of air.
  2. condensation of liquefied air.
  3. liquefaction of steam.
  4. Fractional distillation of liquefied air.
  5. evaporation of liquefied air.
Choose Answer :


(viii)  Which of the following sets of processes uses a gas that ignites with a "pop" sound when a lighted splint is passed through it?

  1. Balloon filling, welding and diving 
  2. Hardening oil, balloon filling and welding
  3. Hardening oil, balloon filling and diving
  4. Fueling rocket, diving and welding
  5. Balloon filling, fueling rocket and diving
Choose Answer :


(ix) Which statement is the most correct about chemistry laboratory?

  1. Is a special room designed for conducting chemical tests.
  2. Is a special room designed for science practicals.
  3. Is a special room designed for keeping apparatuses. 
  4. Is a special room where data analysis is carried out.
  5. Is a special room where students learn chemistry.
Choose Answer :


(x) Which role does the organic matter play in the soil?

  1. Improving water infiltration of the soil.
  2. Accelerating break down of organic matter.
  3. Reserving nutrients thus providing soil fertility.
  4. Converting nitrogen into nitrates.
  5. Providing a room for organic material such as nylons.
Choose Answer :


2. Match the descriptions in List A with the corresponding scientific procedures in List B by writing the letter of the correct response besides the item number in the answer booklet provided.

LIST 1 LIST B
  1. A statement of how the results relate to hypothesis.
  2. A series of investigations.
  3. A statement that identifies an event, fact or situation.
  4. A tentative explanation.
  5. A step in which the researcher explains the results.
  1. Conclusion
  2. Data analysis
  3. Data collection
  4. Experimentation
  5. Hypothesis
  6. Observation
  7. Problem identification
View Ans


SECTION B (70 Marks)

Answer all questions in this section.

3. (a) How many chlorine molecules are in 20 cm of chlorine gas at s.t.p?

View Ans


   (b)Calculate the number of ions present in 5 g of copper II nitrate. (7 marks)

View Ans


4.   (a) Distinguish normal salts from acidic salts based on how they are formed.

View Ans


(b)  Give four uses of salts in daily life.  (7 marks)

View Ans


5.  (a) Distinguish temporary hardness from permanent hardness of water.

View Ans


 (b) With the help of chemical equations, explain how you can remove each type of water hardness in 5(a).  (7 marks)

View Ans


6.  In the industrial preparation of sulphur trioxide, equilibrium is established between sulphur dioxide and oxygen gas as follows:

  (a)(i) Is the forward reaction an endothermic or exothermic process? Give a reason.

View Ans


(ii) How would you adjust temperature and pressure to maximize the proportion of the product at equilibrium?

View Ans


(b) (i) Why is it unfavorable to work with very high pressure and very low temperature in the Contact process?

View Ans


(ii) What catalyst is used to speed up the rate of formation of sulphur trioxide before attaining the equilibrium? (7 marks)

View Ans


7. An atom of element X having atomic number 11 combines with an atom of element Y haying atomic number 9 to form a compound.

(a) Write the formula of the compound and state the type of bond formed in the compound.

View Ans


(b) Give four properties of the compound formed in 7(a).            (7 marks)

View Ans


8. Explain each of the following statements and in each give its balanced chemical equation: 

  1.  Sulphur dioxide in solution is a powerful reducing agent.
  2. Sulphur dioxide in solution act as a bleaching agent.
  3. Sulphur dioxide can reduce chlorine and itself become oxidized.
  4. When hydrogen sulphide is passed through sulphur dioxide gas, yellow deposits are produced. (7 marks)
View Ans


9. (a) Write the chemical symbols for beryllium, boron, neon, nitrogen and phosphorus.

View Ans


 (b) Why some of the elements in 9(a) are assigned symbols with only one letter while others bear symbols with two letters?        (7 marks)

View Ans


10.(a) Give three advantages of using chemical equations over word equations.

View Ans


(b) You are provided with a compound composed of 22.2% zinc, 11.6% sulphur, 22.3% oxygen, and the rest percentage is water of crystallization. Calculate the molecular formula of the compound if its molecular mass is 283. (7 marks)

View Ans


11 . A Form Three student conducted experiments in the laboratory to synthesize nitrogen, ammonia and ethane. The experimental results were tabulated as follows:

Experiment

            Reagents

Conditions

Products

1

Lead nitrate

Heat

Lead oxide, oxygen gas and nitrogen gas

2

Gaseous hydrogen and gaseous nitrogen

Catalyst

Ammonia gas

3

Ethene gas and hydrogen gas

Catalyst

Ethane

Write word equations with corresponding chemical equations to summarize the reactions taking place in each of the experiments I to 3. (7 marks)

View Ans


12. (a) Which ways are the fossil fuels detrimental to the environment? Give four points. 

View Ans


(b)  Briefly explain how biogas is produced by using domestic waste.    (7 marks)

View Ans


SECTION C (15 Marks)

Answer one (1) question from this section.

13.Explain how to handle chemicals having the warning signs of flammable, corrosive, harmful, explosive and toxic in the laboratory.

View Ans


14. Explain six measures for minimizing the environmental degradation caused by extraction of metals in Tanzania.

View Ans


Download Learning
Hub App

For Call,Sms&WhatsApp: 255769929722 / 255754805256

GO TO NECTA EXAMS