CHEMISTRY FORM TWO QUESTIONS WITH ANSWERS
OXYGEN: QUESTIONS
1: Multiple choice.
Choose the most correct answer from the given alternatives.
(i) Which of the following compounds is not likely to contain Oxygen?
A: water
B: Copper oxide
C: ammonia
D: carbonate
(ii) Oxygen supports combustion and it is not used in ________
A: welding
B: respiration
C: incineration
D: extinguishing fire
(iii) Oxygen gas found in the atmosphere because
A: it is a gas
B: it is useful
C: it is denser
D: it is lighter
(iv) Oxygen gas forms water with_______ gas.
A: nitrogen
B: hydrogen
C: carbon dioxide
D: sulphur
(v) ________ is a removal of oxygen from the substance.
A: oxidation
B: reduction
C: redox
D: No answer
(vi) _________ observed when a wooden glowing splint placed in a tool in which hydrogen is contained.
A: yellow colour
B: green colour
C: explosion with pop sound
D: light
(vii) When it is mixed with oxygen a very hot flame is produced.
A: hydrogen gas
B: chlorine gas
C: neon
D: argon
(viii) Which of the following can not be used to prepare oxygen gas?
A: potassium chlorate
B: any compound rich in oxygen
C: electrolysis concentrated sulphuric acid
D: hydrogen peroxide
(ix) The following statement is not true about oxygen.
A: it is used to manufacture ammonia with nitrogen.
B: it burns fuels
C: it is colourless
D: it supports combustion.
(x) The common industrial method of preparing oxygen.
A: electrolysis of copper sulphate
B: electrolysis of bases
C: decomposition of hydrogen peroxide
D: fractional distillation of liquefied air.
2. Matching items.
Match items in list A with responses in list B.
List A
(i) Percentage of oxygen in air we breath
(ii) chemical property of oxygen
(iii) physical property of oxygen
(iv) the property of oxygen to be less denser than air.
(v) Reason for hydrogen to be used in rocket.
List B
A: it oxidises fuel.
B: Tasteless
C: forming metallic oxides
D: it collected over water.
E: 79%
F: used in rockets.
G: 21%
3. Write T for the correct statement and F for incorrect statement.
(i) Oxidation is the addition of oxygen to the substance.
(ii) reduction is removal of oxygen from the substance.
(iii) Oxygen forms basic oxides with non-metals
(iv) Oxygen form acidic oxides with metals
(v) Hydrochloric acid is used to prepare oxygen in the laboratory.
4. List down uses of oxygen
5. (a) State the substance which used to test oxygen.
(b) Explain how we can identify the presence of oxygen?
6. State apparatus used in laboratory preparation of oxygen and their uses.
7. Mention:-
(a) chemical properties of oxygen
(b) physical properties of oxygen
8. Explain why hydrogen collected by downward displacement of water when preparing it in the laboratory?
9. Describe
(a) industrial manufacture of oxygen.
(b) i) laboratory preparation of oxygen by using hydrogen peroxide.
ii) State the function of the manganese IV oxide during preparation of oxygen by using hydrogen peroxide.
10. Give the definitions of oxidation and reduction.
ANSWERS.
1. (i) C vi) D
(ii) D vii) A
(iii) C viii) C
(iv) B ix) A
(v) B x) D
2. (i) G (ii) C (iii) B (iv) D (v)A
3. (i) T (ii) T (iii) F (iv) F (v) F
4. Uses of oxygen.
-it used in respiration process
-it is used in pulp and paper making
-it is used in metal cutting
-it is used as fuel oxidiser in rockets
-it is used in hospital for people with breathing problem.
-it used in glass making
-it is used in treatment of sewage plants.
-it used to manufacture synthetic fuels
-it is used to manufacture chemicals. For example acids and oxides.
5. (a) Chemical test for oxygen is a glowing wooden splint.
(b)oxygen identified is a glowing wooden splint relights when it is lowered into a gas jar of oxygen gas.
6.The following are apparatus used to set the system of preparing hydrogen in the laboratory.
(a) Thistle/dropping funnel
Is used to transfer acidic solution into the flat bottomed flask.
(b) Flat bottomed flask
Is used to mix acidic solution(hydrochloric acid) with zinc granules.
(c) Delivery tube
Is used to transfer hydrogen into beehive stand.
(d) Beehive stand
Is used to connect delivery tube with gas jar.
(e) Gas jar
Is used to collect hydrogen gas
(f) Trough
Is used to hold water.
7. (a)Chemical Properties of Oxygen
(i) It supports burning.
(ii) It is an oxidising agent.
(iii) It reacts with metals to form basic oxides.
(iv) It reacts with non- Metal to form acidic oxides.
(a) Physical Properties of Oxygen
(i) Oxygen is colourless, tasteless and odourless.
(ii) It is slightly dissolves in cold water.
(iii) It is less denser than air.
(iv) It boils at -1830°C.
(v) It freezes at – 2180°C
8. Hydrogen is collected by downward displacement of water because it is less denser than air.
9. (a) Industrial preparation of oxygen is manufactured by fractional distillation of liquefied air after water and dust being removed. Where by different gases that forms air are separated.
-carbon dioxide liquefies at -79°C. At this point it removed from the mixture in which nitrogen and oxygen remained.
-nitrogen liquefies at -196°C and oxygen liquefies at -183°C. In order to obtain liquefied oxygen the mixture boiled then nitrogen boils and rise to the top where it is piped off. The liquid oxygen collected.
(b) (i) Oxygen is mostly prepared in the laboratory by using hydrogen peroxide in presence of manganese oxide.
Hydrogen peroxide decomposed to form water and oxygen then oxygen collected in the gas jar.
(ii) The function of manganese oxide is to speed up the rate of the reaction(decomposition of hydrogen peroxide) because it is used as a catalyst.
10. •Oxidation refers to:-
-the process of adding oxygen to the substance.
-the process of removing hydrogen from the substance.
-the process of removing electron from the substance.
-the process of increasing oxidation number.
•Reduction refers to:-
-the process of adding hydrogen to the substance.
-the process of removing oxygen from the substance.
-the process of adding electron to the substance.
-the process of decreasing in oxidation number.
NB:
>Redox reaction:- is the reaction in which both reduction and oxidation are taking place.
>Oxidizing agent:- is a substance that influence or its presence makes oxidation to take place.
>Reducing agent:- is substance that influence or its presence makes reduction to take place
HYDROGEN: QUESTIONS
1: Multiple choice.
Choose the most correct answer from the given alternatives.
(i) Which of the following compounds is not likely to contain hydrogen?
A: water
B: Copper oxide
C: ammonia
D: water gas
(ii) Hydrogen does not support combustion but it is used as ________
A: water gas fuel
B: respiratory gas
C: oxidant
D: fire extinguisher
(iii) Hydrogen gas is used to fill weather balloons because
A: it is a gas
B: it is heavier
C: it is abundant
D: it is lighter
(iv) Hydrogen gas forms ammonia with_______ gas.
A: nitrogen
B: Oxygen
C: carbon dioxide
D: sulphur
(v) ________ and _______ reacts slowly to produce water.
A: oxygen and helium
B: hydrogen and helium
C: hydrogen and oxygen
D: No answer
(vi) _________ observed when a wooden glowing splint placed in a tool in which hydrogen is contained.
A: yellow colour
B: green colour
C: explosion with pop sound
D: clacking sound.
(vii) When it is mixed with hydrogen a very hot flame is produced.
A: oxygen gas
B: chlorine gas
C: neon
D: argon
(viii) Which of the following can not be used to prepare hydrogen gas?
A: reaction of water with carbon at room temperature.
B: reaction of dilute acid with zinc
C: electrolysis of water
D: reaction of water with certain metals
(ix) The following statement is not true about hydrogen.
A: it is lighter than air
B: it burns with blue flame
C: it is colourless
D: it supports combustion.
(x) The common industrial method of preparing hydrogen.
A: electrolysis of copper sulphate
B: electrolysis of bases
C: decomposition of hydrogen peroxide
D: electrolysis of water.
2. Matching items.
Match items in list A with responses in list B.
List A
(i) water gas fuel
(ii) chemical property of hydrogen
(iii) physical property of hydrogen
(iv) the property of hydrogen to have less denser than air
(v) Reason for hydrogen to be used in production of fuel
List B
A: is reason for it to be filled in weather balloons.
B: Tasteless
C: flammability
D: pop sound
E: reacting with other substances at high temperature.
F: used in rockets.
3. Write T for the correct statement and F for incorrect statement.
(i) Oxidation is the addition of hydrogen to the substance.
(ii) reduction is removal of hydrogen from the substance.
(iii) Hydrogen reacts with chlorine to produce hydrochloric acid.
(iv) Hydrogen is most abundant gas on the earth.
(v) Hydrogen made under the process known as Haber process.
4. List down uses of hydrogen
5. (a) State the substance which used to test hydrogen.
(b) Explain how we can identify the presence of hydrogen?
6. State apparatus used in laboratory preparation of hydrogen and their uses.
7. Mention:-
(a) chemical properties of hydrogen
(b) physical properties of hydrogen
8. Explain why hydrogen:-
(a) collected by downward displacement of water?
(b) is not found in the atmosphere?
9. Describe two methods for industrial manufacture of hydrogen.
ANSWERS.
1. (i) B (vi) C
(ii) A (vii) A
(iii) D (viii) A
(iv) A (ix) D
(v) C (x) D
2. (i) F (ii) E (iii) B (iv) A (v) C
3. (i) F
(ii) F
(iii) T
(iv) F
(v) F
4. Uses of hydrogen include the following.
(i) Hydrogen is used in the synthesis(production) of ammonia.
This is done on large scale through the
laboratory process.
(ii) Hydrogen is used in the Manufacture of margarine.
(iii) Hydrogen is used to produce oxy-hydrogen flame.
This flame can be used for welding and cutting metal.
(iv) it is used to make fuel since it is highly flammable.
5. (a) The substance used to test hydrogen is wooden glowing splint.
(b) Hydrogen identified if explosion with a pop sound observed when the gas come into contact with a wooden glowing splint.
6. The following are apparatus used to set the system of preparing hydrogen in the laboratory.
(a) Thistle funnel
Is used to transfer acidic solution into the flat bottomed flask.
(b) Flat bottomed flask
Is used to mix acidic solution(hydrochloric acid) with zinc granules.
(c) Delivery tube
Is used to transfer hydrogen into beehive stand.
(d) Beehive stand
Is used to connect delivery tube with gas jar.
(e) Gas jar
Is used to collect hydrogen gas
(f) Trough
Is used to hold water.
7. (a) chemical properties of hydrogen include the following.
(i) It combine easily with other chemicals substance at high temperature.
(ii) It does not usually react with other element at room temperature.
(iii) It is highly flammable and burns with a blue of flame.
(iv) It reacts slowly with oxygen to produce water.
(v) It is neither acidic nor basic
(b) Physical Properties of Hydrogen
(i) It is tasteless, colourless and odourless.
(iii) It is lighter than air, Therefore it is in the atmosphere.
(iii) It is only slightly soluble in water.
(iv) It does not support combustion.
8.(a) hydrogen is collected by downward displacement of water because it is slightly soluble in water.
(b) hydrogen is not found in the atmosphere because it is lighter such that it found above the atmosphere.
9. Industrial methods of manufacturing hydrogen include the following.
(i) Electrolysis of water
(ii) Electrolysis of dilute sulphuric acid.
Electrolysis of water.
Electricity used to decompose water into hydrogen and oxygen. In this process hydrogen collected as gas at the cathode.
Electrolysis of dilute sulphuric acid.
Electricity decomposes sulphuric acid into hydrogen and sulphate.
WATER: QUESTIONS.
1. Multiple choice.
Choose the most correct answer from the given alternatives.
(i) The system where water is being recycled
A: water movement.
B: water system
C: hydro-logical cycle
D: water treatment.
(ii) Formation of liquid water from ice is under the process known as ______
A: melting
B: condensation
C: evaporation
D: precipitation
(iii) _________ water generate hydro electric power.
A: cold B: moving C: hot D: atmospheric.
(iv) Usable water obtained after being _________
A: Purified
B: boiled
C: filtered
D:.treated
(v) One of the following is not physical properties of water.
A: it is colourless, odourless and tasteless
B: it is neither acidic nor basic.
C: it is a universal solvent
D: it freezes at 0°C and boils at 100°C
(vi) We get pure water after________
A: being boiled
B: removal of contaminants
C: being filtered
D: removing mud and dust.
(vii) Which of the following statement about water is not true?
A: is used in industries as coolant
B: is used as raw material to produce hydrogen to produce carbon
C: is used as solvent
D: is used as raw material to produce hydrogen gas
(viii) The simplest way to purify water at home.
A: cooling
B: boiling
C: filtering
D: condensing
(ix) During precipitation, water falls in form of.
A: rain and clouds
B: rain, snow and hail
C: water ice
D: vapour
(x) The process of removing contaminants from water is called_________
A: water purification
B: sedimentation
C: electrolysis
D: contamination
2. Matching items.
Choose the correct response from list B that match with item in list A.
List A.
(i) liquid state of water
(ii) solid state of water
(iii) gaseous state of water
(iv) uses of water in agriculture
(v) combination of acidic gases and water vapour.
(vi) using untreated water
(vii) reaction of water and metals to form hydroxides and hydrogen gas.
(viii) Boiling
(ix) swimming
(x) cooling machine.
List B
A: chemical property of water.
B: simple domestic water treatment.
C: may cause eruption and spread of diseases
D: ice, snow and hail.
E: clouds, mist and steam.
F: dew and rain
G: use of water in recreation.
H: lead to occurrence of acidic rain.
I: irrigation.
J: industrial use of water.
3. Why water is said to be a universal solvent?
4. How can we test the presence of water in a substance?
5. Define the following terms.
(i) water treatment
(ii) precipitation
(iii) evaporation
(iv) condensation
(v) water purification
(vi) solubility
(vii) melting
6. (a) Explain the methods of domestic treatment of water
(b) Explain the process of urban treatment of water
7. List down uses of water.
8. Differentiate water treatment from water purification.
9. (a)What are the importance of treating water?
(b) What are the importance using treated water?
10. Analyse physical properties and chemical properties of water.
11. (a) define water cycle
(b) explain processes involved in a water cycle.
ANSWERS.
1. (i).C vi) B
(ii) A vii) B
(iii) B viii) B
(iv) D ix) B
(v) B x) A
2. (i) F vi) C
(ii) D vii) A
(iii) E viii) B
(iv) I ix) G
(v) H x) J
3. Water is said to be a universal solvent because many substances dissolved in it if compared to other solvents.
4. We can identify presence of water by using the following specific tests.
i) Blue Cobalt chloride vapour.
-Water or its vapour will turn cobalt chloride paper from blue to pink.
ii) Anhydrous copper(II) sulphate
Water or its vapour turns
anhydrous copper(II) sulfatecrystals from white to blue.
5. (i) Water treatment
is a process of making unusable water into usable.
(ii) Precipitation
Is a process in which water fall to the earth in forms of rain, hail or snow.
(iii) Evaporation
Is a process where by the water vapour or steam leaves the streams, rivers, lakes or oceans into the air.
(iv) Condensation
Is a process in which water vapour in air get cold and change into liquid that form clouds.
(v) Water purification
is a process of removing contaminants from treated water.
(vi) Solubility
Is a tendency of substances (solutes) to dissolve to form solutions.
(vii) Melting
Is a process of changing from solid substance into liquid substance.
6. (a) methods of treating domestic water include the following
(i) Boiling.
Is a process of heating water and let it to boil at least five minutes before heating is stopped.
(ii) Use of purifiers.
Is a method of treating water where by chemical water purifiers are added in water.
Water purifiers are in forms of liquid or tablet.
(iii) Use of commercial filters.
Is a method of water treatment in which water pass through a charcoal or ceramic element that purifies water.
(b) the following summary explains Urban water treatment.
Tap water used in urban is usual obtained from sources such as rivers, stream and lakes
which are not treated. Processes for treatment of urban water are explained as follows
i. Screening
ii. Reservoirs
iii. Primary filtration
iv. Secondary filtration
v. Disinfection/chlorination
vi. Storage
•Screening
This process involves the removing of floats substance
•Reservoirs
This process involves the storing of water at high up so it flows through gravitation
•Primary filtration
This process involves
i. Filtered water comes from reservoir
through coarse sand (filter medium) to remove particles
ii. Addition of aluminium sulphate to water comes from reservoir to remove smaller particles which was not filtered at coarse sand
•Secondary filtration
This process involves Filtered water comes from primary filtration through finer sand (filter medium) to remove smallest particles
•Disinfection/chlorination
This process involves put Disinfection to water comes from secondary filtration to kill harmful bacteria
•Storage
This process involves to store soft water (comes from Disinfection/chlorination) ready for use
7. Uses of water.
-it used for drinking
-it used for cooling
-it used for cleaning.
For. Example environment
-it used for washing. Eg bodies
-it used to manufacture goods
For. Example food and chemicals
-it used for agriculture activities
For example irrigation.
-it used to generate hydro electric power.
-it used in construction. Eg. Roads
-it used as a solvent.
-it used in transportation.
8. Water treatment is a process of making unusable water into usable.
While
Water purification is a process of removing contaminants from treated water.
There fore when treating water we get useful water but when purifying water we get pure water.
9. The following are importance of water treatment.
(i) it helps to remove harmful bacterial and other parasites which may cause diseases.
(ii) it enables us to get efficient water for different uses. Eg cleaning
(iii) it helps to get suitable water for manufacturing products which are safe for consuption.
(iv) it helps us to get water which is best for laboratory uses and medical facilities.
(b) Importance of using treated water.
(i) it helps to avoid infections and spread of diseases.
(ii) it provides correct result when performing experiments in the laboratory
(iii) it provides safe products for human consuptio when it is used in manufacturing industries.
(iv) it simplifies cleaning and maintains the quality cleaned substance.
10. Physical properties of water
i. It is colourless, odourless and tasteless
ii. Occurs natural in all state of mater
iii. It is universal solvent
iv. Freezing point is 0 ℃
v. Its boiling point is 100 ℃
vi. It has high surface tension
vii. It has high specific heat index
viii. It expands when freezes thus why ice float
over water
ix. It is miscible with many liquids
Chemical properties of water
i. Pure water is neutral (neither acidic nor
basic)
ii. Cold water react with some metals to
form hydroxide and liberate hydrogen gas
iii. Some metals react with steam to give
respective metal oxide and hydrogen gas
11.
(b)Water Cycle stages
Water cycle is made up to four main stages which are
i. Evaporation (include transpiration)
ii. Condensation
iii. Precipitation
iv.Collection
Evaporation (include transpiration)
Water from rivers, lakes, stream, sea, ponds etc evaporate to air.
Plants lose water in form of vapour by
transpiration while animal and human being lose water through respiration and
sweating
Condensation
Water vapour obtained by evaporation,
transpiration, perspiration and sweating in the air gets cold and changes back into liquid to form clouds
Precipitation
Rain start when air fails to hold condensed
water and final results rain
Collection
Takes place when rain water back to the
ground which may run over the soil and
collected in the rivers, lakes, stream, sea, ponds where cycle stars all over again.
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