Chemistry

END OF YEAR ASSESSMENT 2022 

SENIOR ONE  

CHEMISTRY: THEORY

SECTION A

(Attempt all questions in this section) 

1. (a) Which piece of laboratory apparatus would be most suitable for each of the 

​Following activities? ​ ​ ​ ​ ​ ​ ​ ​(06 marks) 

(i) (i)        Holding 50 cm³ of boiling water. ………………………………………………………. 

(ii) (ii)     Melting a crystal over a Bunsen burner……………………………………………… 

(iii) (iii)   Pouring 50 cm³ of acid from one container to another……………………………… 

(iv) (iv)   Measuring exactly 30 cm³ of water…………………………………………………….. 

(v) (v)     Removing substances from a reagent bottle………………………………………… 

(vi) (vi)   Weighing 100 grams of sodium chloride……………………………………………… 

(b) Provide appropriate advice to a student who accidentally spill water near an electrical equipment.  ​ ​ ​ ​ ​ ​ ​​(04 marks)  

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2. (a) Complete the following sentences about fractional distillation using words from the list below.

Boiling, condenses, cooled, heated, higher, Lower, melting, mixture, pressure, vaporizes 

Petroleum is a ………………………. of hydrocarbons. This mixture is ………………………. and the hydrocarbons vaporize. The temperature in the fractionating column is ………………………. at the top than at the bottom. As the vapours move up the column, each hydrocarbon fraction ………………………. when the temperature in the column falls below the ………………………. point of the hydrocarbon fraction.

(b) A student placed some crystals of salt at the bottom of a beaker of distilled water. She left the contents of the beaker to stand for one hour.  

​The diagram below shows her observations.  ​ ​ ​​(05 marks) 

After one hour, all the salt had disappeared but the solution at point X tasted salty. 

​(i) Use the kinetic particle theory to explain these observations. ​(02 marks) 

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3.  (a)  After use, a non-luminous flame should be put off or adjusted to a luminous flame.  

​Explain. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​(2 mks) 

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(b) (b)    State any 6 safety rules in the laboratory. ​ ​ ​​ (6 mks) 

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4. Name three substances that undergo sublimation.  ​ ​ ​​(3 mks) 

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(b) A student took a sample of seawater and heated it using the apparatus shown below. 

(i) (i)                 What is the name given to the process shown in the diagram? (01 mark) 

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(ii) (ii)​State the name of the piece of apparatus labelled A.  ​​(01 mark) 

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(iii) (iii)            Explain the function of the condenser. ​ ​ ​​(02 marks) 

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(iv) (iv)            State the boiling point of pure water.  ​ ​ ​​(01 mark) 

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5.    (a)  What is fractional distillation? ​ ​ ​ ​ ​ ​​(1 mk) 

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(i) (i)      Give two applications of fractional distillation. ​ ​​ ​(2 mks) 

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         (b) The pie chart shows the composition of air. 

(i) (i)                 What is the percentage of nitrogen in the air?  ​​(01 mark) 

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(ii) (ii)​Apart from nitrogen and oxygen, state the names of two gases present in unpolluted air.        (02 marks) 

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SECTION B  

(Attempt any TWO questions) 

6. (a) Read the passage below and answer the questions that follow.  

Almost all the industries produce poisonous chemicals as their waste products. These are called chemical waste or industrial wastes. These wastes are discharged untreated in nearby water bodies. In this way, the water bodies get polluted with chemicals. The chemicals present are the compounds of harmful metals such as mercury, cadmium, lead, arsenic and nickel. These may also include detergents and polychlorinated biphenyls (PCBs). These chemicals can kill aquatic animals and plants. They also cause severe disorders in humans such as cancer and nervous disorders. 

(i) (i)                 Give a suitable title to the passage above.  ​ ​​(01 mark) 

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(ii) (ii)​What does it mean by chemical waste? ​ ​ ​​(01 mark) 

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(iii) (iii)            Chemical waste can cause ………………………. And…………………………… in humans.        (02 marks) 

(iv) (iv)            Compounds of which elements are present in chemical waste?(03 marks) 

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(v) (v)               In which area could the photograph have been taken from in Uganda?  

(01 mark) 

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(b) Explain briefly Why polythene should be banned in Uganda?   ​(03 marks) 

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7. (a) Look at the pictures below and answer questions that follow. 

(i) (i)        How are the events in the pictures relevant in our lives?  ​​(04 marks) 

(ii) (ii)     What would happen if the events in the pictures didn’t happen? ​(03marks) 

(iii) (iii)   Write short notes on the importance of Chemistry in our lives. ​(03marks) 

8. Read the information below and answer the questions that follow 

Chemistry as a subject is sometimes learnt through practical activities known as experiments done in the laboratory. In the laboratory, you will find equipment, materials and chemicals which are used when performing these experiments. 

Chemical substances used in an experiment are known as reactant substances. Students need to conduct themselves with care and in an orderly manner while in the laboratory so as to avoid injuries and accidents that could occur. Safety rules and regulations have been put in place to guide you as a student when using the laboratory. 

​(i) ​Write short notes on each of the work areas in a chemistry laboratory  

a) a)     Preparation room 

b) b)     Storage room 

c) c)      Student working area 

d) d)     Fume chamber 

e) e)      Teacher’s working counter 

f) f)       Safety exit  ​ ​ ​ ​ ​ ​ ​ ​(10 marks) 

9. (a) Identify the flames shown in the diagrams below, (i) Name the parts labelled 

​X and Y, Z and W.   ​ ​ ​ ​ ​ ​ ​(04 marks) 

(ii) (ii)​Suggest the appropriate apparatus for holding test tubes when heating liquids.         (01 mark) 

(iii) (iii)            Explain your answer in (ii) above.  ​ ​ ​​(02 marks) 

​(b)  Explain why most laboratory apparatus are made of glass. ​(03 marks) 

10. (a) A student investigated food dyes using paper chromatography. 

This is the method used 

1. Put a spot of food coloring X on the start line. 

2. Put spots of four separate dyes, A, B, C and D, on the start line. 

3. Place the bottom of the paper in water and leave it for several minutes. Figure shows the apparatus the student used. 

(ii) Write down one mistakes the student made in setting up the experiment and explain what problems one of the mistakes would cause. ​(01 mark) 

(b) Another student set up the apparatus correctly, Figure below shows the student’s results. The result for dye D is not shown 

(iii) (iii)   Calculate the Rf value of dye A Give your answer to two significant figures. 

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(iv) (iv)   Explain how the different dyes in X are separated by paper chromatography 

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(b) The graph below shows heating of ice until boiling starts. 

(i) Briefly state what happens in regions:    (04 marks) 

S

***END****

“MERRY CHRISTMAS AND HAPPY NEW YEAR” 

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