Form 1 Chemistry Exams and Marking Schemes Free

Form 1 Chemistry Exams and Marking Schemes Free

NAME……………………………………………………………………………ADM………

 

CLASS…………………………………………………………………………………………

FORM 1

233

CHEMISTRY

2 HOURS

JOINT EVALUATION TERM 3 2023

THEORY

2 HOURS

INSTRUCTIONS TO STUDENTS

1. Write your name and admission number in the spaces provided
2. Answer ALL the questions in the spaces provided
3. KNEC mathematical table and silent non-programmable electronic calculators may be used for calculations
4. All working MUST be clearly shown where necessary
5. Students should check the question paper to ascertain that all the pages are printed as indicated and that no question is missing
6. Students should answer the questions in English

 

FOR EXAMINERS USE ONLY

QUESTIONS	MAXIMUM SCORE	CANDIDATE’S SCORE
1-16	80

 

1. State one importance of studying chemistry (1 mark)

…………………………………………………………………………………………………………………………………………………………………………………………………….

2. a)Name three illegal drugs (3 marks)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

1. b) State three ways of preventing drug abuse. (3 marks) ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
2. Complete the following table (8mks)
3. State two laboratory safety rules (2mks)

………………………………………………………………………………………………………………………………………………………………………………………………

5. The apparatus below were used to separate a mixture of liquid A and B.

 

1. State two properties of liquids that make it possible to separate using such apparatus.

2 marks)

…………………………………………………………………………………………………………………………………………………………………………………………………..

1. Give the name of the above apparatus. (1 mark)

………………………………………………………………………………………………

6. Describe how you can separate a mixture of sand and common salt(3 marks)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..

7. The diagram below shows a Bunsen burner when in use

 

C

B

 

 

A

1. Name the regions labelled B and C. (2 marks)

B………………………………………………………………………………………………

C…………………………………………………………………………………………………………………

1. What is the function of the part labeled A? (1 mark)

…………………………………………………………………………………………………

8. State three differences between physical and chemical change. (3 marks)

TEMPORARY	CHEMICAL

 

9. i) Differentiate between an acid and base(2 marks)……………………………………………………………………………………………………………………………………………………………………………………
10. The following is a list of pH values of some substance: SubstanceM N V X Z

pH 10.6 ,7.2 ,13.2 ,5.9, 1.5 respectively Identify:

1. Strong acid (1 mark)

………………………………………………………………………………………………

1. Weak base (1 mark)

………………………………………………………………………………………………

10. The diagram below represents the apparatus used to prepare and collect oxygen.

Hydrogen peroxide

 

 

 

 

Solid Q

Solid P

1. Complete the diagram to show how oxygen gas is collected. (2 marks)

 

1. Name solid P and Q (2 marks)

P………………………………………………………………………………………….

Q………………………………………………………………………………………..

 

• Write the word equation to show the reaction that produces oxygen gas.(1 mark)

 

 

1. State two physical properties of oxygen.(2 marks)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

 

 

1. State three uses of oxygen gas.(3marks)

……………………………………………………………………………………………………………………………………………………………………………………………………..

………………………………………………………………………………………………….

11. A form one student wanted to separate and obtain iodine and sodium chloride (common table salt) from amixture of the two. He set the experiment set up shown below.

(a). the mixture was heated for some time and left to cool. On cooling, shiny black crystals and white crystalswere observed on the surface of the watch glass and in the beaker respectively. Name:

1. Shiny black crystals                                                                            (1mk)

……………………………………………………………………………………………………

1. White crystals (1mk)

…………………………….…………………………………………………………………….

 

(b). what was the purpose of the cold water in the watch glass? (1mark)

…………………………………………………………………………………………………

(c). what property of iodine makes it be collected on the watch glass as shown? (1mark)

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(d). Explain why it is possible to separate a mixture of iodine and sodium chloride. (1mark)

…………………………………………………………………………………………………

12. A candle was burnt using the apparatus shown below. The initial volume of measuring cylinder was90cm3. The apparatus was allowed to cool and the volume of air in the measuring cylinder had dropped to 70cm3.
13. Why was the volume recorded when the air was cooled? (1mk)

………………………………………………………………………………………………

1. What was the purpose of sodium Hydroxide? (1mk)

………………………………………………………………………………………………

1. Use the results given to calculate the percentage of oxygen in air. (2mks)

 

 

 

 

 

 

 

13. The set up below was used to study some properties of air

 

State and explain two observation that would be made a t the end of the experiment.   (3mks)                                                                                                                             ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..

 

14. The diagram below represents three methods for collecting gases in the laboratory
15. a) Name the methods shown in the diagram (3mks)

i………………………………………………………………………………………………

ii…………………………………………………………………………………………………

iii……………………………………………………………………………………………

1. State with reasons the most suitable methods for collecting each of the following gases.
2. Oxygen (1mk)

……………………………………………………………………………………………

1. Hydrogen (1mk)

…………………………………………………………………………………………..

15. a) The diagram below shows spots of pure substance A, B, and C on a chromatography paper. Spot D is that of a mixture after development, A, B and C were found to have moved 8cm, 3cm and 6 cm respectively.

D has separated into two spots which had moved 6cm and 8 cm

(i) On the diagram

I Label the baseline (origin) (1 mark)

 

II Show the positions of all the spots after development (3 marks)

 

 

(ii) Identify the substances present in the mixture D (2 marks)

………………………………………………………………………………………………

(b) Describe how solid ammonium chloride can be separated from a solid mixture of ammonium chloride andanhydrous calcium chloride(2 marks)………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..

(c) The table shows liquids that are miscible and those that are immiscible

 

Liquid	L3	L4
L1	Miscible	Miscible
L2	Miscible	Immiscible

 

Use the information given to answer the questions that follow

• Name the method that can be used to separate L1 and L3 from a mixture of two

(1mk)

…………………………………………………………………………………………..

• Describe how a mixture of L2 and L4 can be separate

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… ……………………………………………….

16. Complete the word equations for the following reactions; (3mks)

(a) Sodium carbonate + hydrochloric acid =

 

(b) Zinc   +   sulphuric acid =

 

(c) Potassium hydroxide   + nitric acid    =

17. In an experiment, dry hydrogen chloride gas was passed through heated Zinc turnings as shown in the diagram below. The gas produced was then passed through heated Lead II Oxide.

 

Tube L            Zinc turnings

Lead (II) oxide

tube V

Dilute hydrochloric acid               heat

Flask z

Concentrated

sulphuric VI acid

 

1. What is the function of the water in the flask Z?(1mark)

……………………………………………………………………………………………………………………………………………………………………………………………………

 

1. Write word equation for the reaction that took place in the combustion tubes.(4marks)

……………………………………………………………………………………………………………………………………………………………………………………………………

 

• State three observations made when a piece of potassium is dropped in water (3mks)

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_______________________________________________________________________________________________

CHEMISTRY FORM 1

END OF TERM 3

MARKING SCHEME

1. – Forms foundation for professional training. (1mk for any one)

— Provides man with knowledge necessary for manufacture of basic necessities

— Enables man to understand and deal with environmental factors affecting him

 

2. a) Heroin

Cocaine

Mandrax

Morphine

Bang

Any other drug abused

 

1. b) Proper use of all medicinal drugs

Never use any illegal drug

Stay away from those who use or sell drugs

Involving in any other useful work

 

3

 

4. Laboratory safety rules

-no running in the lab

-no performing an authorized practical

-no smelling gases directly

-no eating in the laboratory

Any other laboratory rule

 

5 (a) The apparatus below were used to separate a mixture of liquid A and B.

State two properties of liquids that make it possible to separate using such

Apparatus. (2 marks)

– Immiscible

– Different densities

 

(b) Give the name of the above apparatus. (1 mark)

– Separating funnel

 

6. Add water to the mixture and stir, √1 common salts dissolves while sand insoluble.

– Filter√1 to obtain sand as residue and common salts as filtrate. ü 1

– Evaporate the filtrate to obtain crystals√1 of common salts.

NB: Steps must be systematic, otherwise penalize fully.

 

7 i. B – unburnt gas/colorless region ü 1

C – Pale blue region ü 1

 

1. Regulate the amount of air entering the chimney by Closing and opening of air holesü 1

 

8. Physical Chemical

– No new substance is formed -New substance is formed

– No energy is either given out or absorbed – Energy is usually given out or absorbed

– Mass of the substance does not change – Mass of the substance changes

– Change is usually reversible – Change is usually irreversible

 

9. i.

Acids	Bases
(i)              Reacts with bases to give salt and water only	(i)              Reacts with acids to give salt and water
(ii)            Have a PH of less than 7	ii)Have PH more than 7
(iii)Changes blue litmus paper red	(iii)changes red litmus paper blue

Any other correct difference.

 

1. a) Z,
2. b) M

 

10. i.

 

ii)P – Manganese (IV) oxide

Q – Anhydrous calcium chloride /calcium oxide

 

Manganese (IV) oxide

iii. Hydrogen peroxide Water + Oxygen

 

iv)- Colorless

– Odorless

– Slightly soluble in water

 

1. – Used in hospitals by patients with breathing difficulties

– Used when mixed with helium in deep sea divers & mountain climbers

– Burn fuels that propel rockets

– mixed with acetylene used for welding

– remove impurities during steel making

– remove impurities during

 

11(a) shiny-black crystals are iodine crystals

-white crystals are sodium chloride solid

 

(b). to cool and condense the iodine vapour to form iodine solid.

(c) . Iodine sublimes when heated.

(d). iodine sublimes while sodium chloride does not.

 

12(a) to allow all oxygen to be used up and also to allow the gas to contract/

Cater for any expansion of gases

(b) To absorb carbon (IV) oxide which was produced by the burning candle

(c) % of oxygen 90 – 70 x 100 = 22.2%

 

 

90

 

13-Iron will be covered by a reddish brown substance/coating/rust

-Water in test tube rise and water in a beaker drops

Explanation:

Iron Combines with oxygen in a presence of moisture to form hydrated Iron (III) oxide /

Rust water rises up to occupy the space which was occupied by oxygen in the tube.

 

14 (a) (i) Over water

(ii) Upward delivery/ downward displacement of air

(iii) Downward delivery/ upward displacement of air

 

(b) (i) Over water : it is slightly soluble in water

 

(ii) Upward delivery: It is less dense than air

 

 

 

15

 

 

(ii) A and C

 

1. b) Since NH4CL sublimes but CaCl2 does not; sublimation process would do .Heat the mixture.

Ammonium chloride sublimates into vapour and condenses on the cooler part of the heating

Tube. Calcium chloride will remain on the bottom of the heating tube.

 

1. c) i) Fractional distillation
2. ii) Separating funnel method

 

Since the two liquids are immiscible, pour both the liquids in a separating funnel and

Allow settling, the denser liquid will settle down and the less dense will form a second

Layer on top. Open the tape and run out the liquid in the bottom layer leaving the liquid

In the second layer in the funnel.

16a) =sodium chloride+ carbon IV oxide+ water

=Zinc sulphate+ hydrogen gas

=Potassium nitrate+ water

 

• What is the function of the water in the flask?
• To dissolve the unreacted Hydrogen chloride gas.
• Write equations for the reactions that took place in the tubes.

 

L – 2HCl_(g) + Zn_(s)                   ZnCl_2(s) + H_2(g)

V – PbO_(s) + H_2(g)                    H₂O_(g) + Pb_(s)

• – Darts on surface of water
• Spontaneously burns with a purple flame
• Produces a hissing sound