Kuulchat - WASSCE June 2017 science

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OBJECTIVE TEST

The volumetric flask is used in the laboratory to

prepare standard solution.

separate a mixture of immiscible liquids.

carry out simple distillation.

dry substances.

The internal diameter of a wedding ring could be measured most accurately using a

half-metre rule.

tape measure.

micrometer screw gauge.

vernier callipers.

Which of the following organisms transmits the protozoa which causes trypanosomiasis in cattle?

Louse

Mosquito

Tick

Tsetse fly

Biological control of malaria involves

draining breeding grounds of mosquitoes.

spraying surfaces on which mosquitoes settle with insecticides.

introducing fish into ponds to feed on larvae of mosquitoes.

burying empty cans.

Water is referred to as universal solvent because it

dissolves most substances.

changes blue litmus solution to red.

reacts with base to produce salt.

has pH of 7.

The heat energy needed to convert a quantity of liquid at its boiling point to vapour is referred to as

latent heat of fusion.

specific latent heat of fusion.

latent hat of vaporization.

specific latent heat of vapourization.

A feeding association in which one partner benefits while the other loses is known as

commensalism.

mutualism.

parasitism.

symbiosis.

Which of the following symptoms is associated with anthracnose in cassava?

Rotting of tubers

Reddish colour of older leaves.

Wilting of the leaves.

Irregular spots on older leaves.

Which of the following activities could control fungal diseases in a backyard garden?

I. Planting resistant varieties
II. Practicing good farming sanitation
III. Destroying affected plants by burning

I only

I and II only

II and III only

I, II and III

10.

The contraction of the biceps muscle in humans is likely to result in

straightening of the forearm.

bending of the forearm.

contraction of the triceps.

movement of the scapula towards the sternum.

11.

Alpha decay involves the emission of

electrons.

neutrons.

helium nuclei.

gamma rays.

12.

Hydrolysis of fats and oils in the presence of a base results in the production of

soapy detergent and glycerol.

soapless detergent and glycerol.

soapy detergent and alcohol.

soap and fatty acids.

13.

The role of oxygen in seed germination is to

provide energy for cell division and growth.

soften the seed coat.

dissolve the stored food.

transport food substances to site of growth.

14.

Which of the diagrams below illustrates a body in a stable equilibrium?

15.

Liming the soil improves its fertility by

neutralizing soil acidity.

decreasing the activity of soil microorganisms.

improving soil structure.

reducing soil erosion.

16.

Radioisotopes are used in

I. treatment of cancer.
II. food preservation.
III. pest control.
IV. plant breeding.

Which of the statements above are correct?

I, II and III only

I, II and IV only

II, III and IV only

I, II, III and IV

17.

A 50 g sample of garden soil weighs 45 g after drying in an oven. Determine the percentage moisture content of the sample.

95%

20%

11%

10%

Percentage = $\frac{Number}{Total}$ x 100%

Moisture = 50 g - 45 g = 5 g

Percentage moisture = $\frac{5 g}{50 g}$ x 100% = 10%

18.

Ectopic pregnancy in humans may result in

I. rupture of the fallopian tube.
II. bleeding.
III. weakness of the abdominal muscles.

Which of the statements above are correct?

I and II only

I and III only

II and III only

I, II and III

19.

Given that the Avogadro's constant is 6.02 x 10²³, determine the number of atoms in 0.01 moles of a substance.

6.02 x 10²⁰ atoms

6.02 x 10²¹ atoms

6.02 x 10²³ atoms

6.02 x 10²⁴ atoms

20.

An object is placed 150 cm in front of a vertical plane mirror. The image formed is

same size as the object.

situated 150 cm from the object.

real and erect.

diminished.

21.

Which of the following benefits could be derived by a farmer from the practice of mulching?

I. Control of growth of weeds
II. Improvement in soil structure
III. Reduction of soil erosion

I and II only

I and III only

II and III only

I, II and III

22.

One of the functions of the human vertebral column is to

enclose and protect the brain.

form a hollow to accommodate the heart.

hold the lungs in position.

support the head.

23.

A force of 60 N was used to raise a load of 300 N. Determine the mechanical advantage of the machine.

360

18000

Mechanical Advantage

Mechanical Advantage = $\frac{Load}{Effort}$

Load = 300 N
Effort = 60 N

Mechanical Advantage = $\frac{300 N}{60 N}$ = 5

24.

The IUPAC name of the compound with the formula Cu(NO₃)₂ is

copper (II) trioxonitrate (V).

copper (I) trioxonitrate (V).

copper trioxonitrate (IV).

copper (IV) trioxonitrate (III).

25.

The function of the pancreatic juice in the digestive system of humans is to break down

I. starch to sugars.
II. proteins to peptides
III. fats to fatty acids and glycerol.
IV. peptides to amino acids.

Which of the statements above are correct?

I and II only

III and IV only

I, II and III only

II, III and IV only

26.

Which of the following steps are required in the scientific approach to problem solving?

I. Identifying a problem
II. Carrying out experiment
III. Analysing results of experiment
IV. Drawing conclusions

I and II only

I, II and III only

II, III and IV only

I, II, III and IV

27.

Grafting is a technique in crop production in which a

scion and a bud are joined together.

scion and a root stock are joined together.

stem and a root stock are joined together.

stem and a scion are joined together.

28.

Which of the following statements about a step-down transformer is/are correct?

I. more turns in the secondary coil than in the primary coil
II. less turns in the secondary coil than in the primary coil
III. higher voltage in the primary coil than in the secondary coil

I only

II only

I and II only

II and III only

29.

Nerve impulses are carried into a nerve cell in humans by the

synapse.

dendrite.

mitochondrion.

myelin sheath.

30.

A 500 cm³ of a solution contains 0.50 mol of HCl. Determine the molar concentration of the solution.

0.03 M

0.25 M

0.50 M

1.00 M

Concentration

Concentration = $\frac{Mole}{Volume}$

Mole = Concentration x Volume

Note: the volume is in dm³.

Mole = 0.50 mol

Volume = 500 cm³ = $\frac{500}{1000}$ dm³ = 0.5 dm³

Concentration = $\frac{0.5 mol}{0.5 {cm}^{3}}$ = 1.0 mol dm^-3 or 1.0 M

31.

Which of the following statements explain why a boat floats in water? The boat floats because

I. the upthrust on it equals the weight of water it displaces.
II. its average density is less than that of the water.
III. upthrust is equal to the volume of water displaced.

I and II only

I and III only

II and III only

I, II and III only

32.

Lack of calcium in the soil will result in

stunted growth of plants.

chlorosis in leaves.

retardation in seed germination.

yellowing of trips and margins of older leaves.

33.

Which of the following chemical compounds gives off ammonia gas when heated with calcium hydroxide?

NaOH

Na₂CO₃

NH₄Cl

K₂SO₄

34.

The rate of evaporation of a liquid could be increased by

decreasing the surface area

reducing the temperature.

maintaining the temperature.

removing the vapour as it forms.

35.

Which of the following elements is a macro plant nutrient?

Boron

Copper

Manganese

Phosphorus

36.

The temperature of a body is 60 °C. The body's temperature in kelvin is

60 K

213 K

273 K

333 K

37.

Which of the following properties are associated with ionic compounds?

I. They are soluble in water
II. They have high melting points
III. They conduct electricity in aqueous solution

I and II only

I and III only

II and III only

I, II and III

38.

A vehicle moving at a velocity of 20 ms^-1 decelerates to rest at 5 ms^-2. Determine the distance it moves from the point of deceleration to rest.

20 m

40 m

60 m

80 m

v = u + at

Where v = final velocity, u = initial velocity, a = acceleration and t = time

When the body comes to rest, the final velocity is 0

Deceleration is negative.

Initial velocity = 20 ms^-1

0 = 20 + (-5)t

-20 = -5t

Divide both sides by -5

t = $\frac{-20}{-5}$ = 4s

s = ut + $\frac{1}{2}$ at²

Where s = distance, u = initial velocity,a = acceleration and t = time

u = 20 ms^-1

t = 4 s

a = - 5ms^-2

s = 20 x 4 + $\frac{1}{2}$ x (-5) x 4²

s = 80 + $\frac{1}{2}$ x (-5) x 16

s = 80 - 40 = 40 m

39.

Duralumin is made of aluminium and

lead.

iron.

copper.

zinc.

40.

Which of the following functions is/are associated with the endoplasmic reticulum of a living cell?

I. Supports the ribosomes
II. Provides large surface area for chemical reaction
III. Provides mechanical support to the cytoplasm

I only

I and II only

II and III only

I, II and III

41.

An organism used in the production of alcoholic beverages is

bacterium.

protozoan.

virus.

yeast.

42.

Which of the following advantages are associated with farm yard manure? It

I. is easy to prepare
II. absorbs and retains moisture
III. encourages rapid weed growth
IV. is needed in large quantities

I and II only

III and IV only

I, II and III only

II, III and IV only

43.

The primary function of the Eustachian tube in the mammalian ear is to

protect the ear drum.

equalize pressure on both sides of the ear drum.

balance the human body.

amplify sound.

44.

Saturated hydrocarbons are characterized by the presence of

single covalent bond between carbon atoms.

double covalent bond between carbon atoms.

triple covalent bond between carbon atoms.

single bond between carbon and hydrogen atoms.

45.

Which of the following groups of characteristics in humans is classified as phenotype?

Eye colour and height

Eye colour and blood group

Height and sickle cell

Blood group and height

46.

The S.I unit of potential difference is

ampere.

ohms.

volts.

watts.

47.

Magnesium is classified as a metal because it

has a low density.

has high tensile strength.

is brittle.

is a solid.

48.

Which of the following colours is a primary colour?

Cyan

Green

Purple

Violet

49.

Which of the following statements are reasons why farmers breed rabbits?

I. Fast growth
II. Good litter
III. Large carcass

I and II only

I and III only

II and III only

I, II and III

50.

Which of the following plant seeds undergo hypogeal germination?

Cowpea

Flamboyant

Maize

Castor oil

THEORY QUESTIONS

(a)

(i)

What is meant by the term seed dispersal?

(ii)

State three ways in which seed dispersal is important.

(b)

(i)

Define potential energy?

(ii)

A 400 g orange on a tree is 120 cm above the ground. Calculate the potential energy of the orange.

[g = 10 ms^-2]

(c)

Give two examples each of the following types of fertilizer:

(i)

inorganic fertilizers;

(ii)

organic fertilizers.

(d)

Three liquids, dilute acid solution, alkaline solution and distilled water, were kept in unlabelled identical reagent bottles.

Describe briefly a test that could be performed to identify each of the liquids.

Show Solution

(a)

(i)

Seed dispersal is the spreading of seeds away from the parent plant.

(ii)

Ways in which seed dispersal is important

1. It prevents overcrowding of seedlings
2. It prevents competition for resources between seedlings and parent plant (or between seedlings)
3. It allows plants to colonize new habitats/areas/lands
4. It minimizes epidemic diseases among seedlings
5. It prevents total destruction of plants by natural disasters (or it prevents plants from extinction)
6. It ensures that few plants are eaten by predators
7. It results in diversity of vegetation in any given location (or it results in availability of a plant species in many widely dispersed areas)

(b)

(i)

Potential energy is the energy possessed by a body due to its position above a reference point (or the ground or relative to others).

(ii)

Potential Energy (P.E) = Mass (m) x Acceleration due to gravity (g) x Height (h)

Mass = 400 g = $\frac{400}{1000}$ kg = 0.4 kg

Height = 120 cm = $\frac{120}{100}$ m = 1.2 m

Acceleration due to gravity = 10 ms^-2

Potential Energy = 0.4 kg x 10 ms^-2 x 1.2 m

Potential Energy = 4.8 J

(c)

(i)

Examples of inorganic fertilizers

1. NPK
2. Sulphate of ammonia
3. Urea
4. Muriate of potash/suphate of potash
5. Potassium nitrate
6. Rock phosphate
7. Sodium nitrate
8. Potassium chloride
9. Calcium nitrate
10. Ammonium nitrate

(ii)

Examples of organic fertilizers

1. Compost
2. Farmyard manure
3. Pig dung
4. Cow dung
5. Green manure
6. Fish manure
7. Poultry droppings
8. Sewage
9. Guano

(d)

Identification of dilute acid solution, alkaline solution and distilled water

Test

Red litmus paper and blue litmus paper are separately placed in each liquid

Observation

Solution	Red Litmus Paper	Blue Litmus Paper
Dilute acid	No colour change/colour remains the same/retains color	Turns red
Alkaline	Turns blue	No colour change/colour remains the same/retains color
Water	No colour change/colour remains the same/retains color	No colour change/colour remains the same/retains color

(a)

(i)

Explain the term ration as used in animal production.

(ii)

Give three reasons for feeding animals with a balanced diet.

(b)

(i)

State three processes involved in purifying water to be supplied to a community.

(ii)

What is the function of liquid ammonia in refrigerators?

(c)

(i)

What does the expression plastics are insulators mean?

(ii)

A simple electrical circuit has a supply delivering 1.5 V. If the current in the circuit is 0.5 A, calculate the resistance.

(d)

Explain each of the following ecological terms:

(i)

community;

(ii)

population;

(iii)

ecosphere.

Show Solution

(a)

(i)

Ration is the amount of total feed provided/served to an animal in a day/24 hour period.

(ii)

Reasons for feeding animals with a balanced diet

1. For proper growth
2. To prevent deficiency diseases
3. For production of healthy young ones
4. For repair of worn-out tissues
5. For energy
6. For replacement of worn-out tissues

(b)

(i)

Processes involved in purifying water to be supplied to a community

1. Screening
2. Filtration
3. Sedimentation
4. Coagulation/flocculation/addition of alum
5. Chlorination/disinfection/sterilization
6. Aeration
7. Taste and odour control by addition of calcium hydroxide
8. Corrosion and scale control

(ii)

Function of liquid ammonia in refrigerators

It vaporizes and takes away heat/brings about cooling/freezing.

(c)

(i)

The expression plastics are insulators mean plastics do not easily conduct/allow electricity/heat to pass through them

The expression plastics are insulators mean plastics do not conduct electricity or heat.

(ii)

Voltage

Voltage(V) = Current(I) x Resistance(R)

Resistance(R) = $\frac{Voltage(V)}{Current(I)}$

Voltage = 1.5 V

Current = 0.5 A

Resistance = $\frac{1.5 V}{0.5 A}$ = 3 Ω

(d)

(i)

Community is a population of different species living in a particular habitat/interacting with each other.

(ii)

Population is a group of organisms/individuals of the same species occupying a particular habitat.

(iii)

Ecosphere is part of the Earth/atmosphere that supports life.

Ecosphere is the part of the universe habitable by living organisms.

(a)

(i)

Give three reasons why water is not a good thermometric liquid.

(ii)

Give the reason why water is a good cooling agent in machines.

(b)

(i)

What is an enzyme?

(ii)

State three factors that affect the action of enzymes.

(c)

List three characteristics each of the following breeds of farm animals:

(i)

layers;

(ii)

dairy cattle.

(d)

(i)

Define the term hydrocarbon?

(ii)

Draw the structural formula of:

α)

ethane;

β)

ethene.

Show Solution

(a)

(i)

Reasons why water is not a good thermometric liquid

1. It shows anomalous property/behaviour
2. Water clings to the capillary tubing/wets glass
3. It vaporizes/condenses in tubing
4. It is transparent and therefore difficult to read its level through the glass
5. It is a poor conductor of heat
6. It freezes at 0°C and boils at 100°C and hence range is not wide
7. It has high specific heat capacity
8. It does not expand uniformly (over a wide range of temperature)

(ii)

Reason why water is a good cooling agent in machines

1. What has a high specific heat capacity/it can absorb a lot of heat without breaking down itself
2. It has low viscosity/it flows easily
3. It is neither basic nor acidic (water is neutral)

(b)

(i)

An enzyme is a chemical that initiates/speeds up chemical reactions in living organisms

An enzyme is a biological catalyst.

(ii)

Factors that affect the action of enzymes

1. Temperature
2. pH/level of acidity or alkalinity
3. Substrate concentration
4. Enzyme concentration/surface area of substance
5. Product concentration
6. Inhibitors or activators

(c)

(i)

Characteristics of layers

1. They have large space between pelvic and breast bones
2. They have large/wide oval or moist or warm vent
3. They have bright/red/waxy/warm large combs and wattles
4. They have large and soft/pliable space between pelvic bones (or flexible pubic bones)
5. They have bright plumage
6. They have deep/soft abdomen without body fat
7. They have bright/large/prominent/sparkling eyes
8. They have feathers ragged/dirty
9. They are normally active/alert to their surroundings
10. They are heavy/large

(ii)

Characteristics of dairy cattle

1. They have well-developed/large udder
2. They have quiet character/they are docile
3. They are wedged-shaped/they are triangular in shape
4. They have large body capacity
5. They have thin long legs
6. They have slow growth rate

(d)

(i)

Hydrocarbon is a compound that contains carbon and hydrogen only.

(ii)

α)

Structural formula of ethane

Note:

1. General formula for alkane = C_nH_{2n + 2}

2. For Eth, n = 2

3. C_nH_{2n + 2} = C₂H_{2 x 2 + 2} = C₂H_{4 + 2} = C₂H₆

β)

Structural formula of ethene

Note:

1. General formula for alkene = C_nH_2n

2. For Eth, n = 2

3. C_nH_2n = C₂H_{2 x 2} = C₂H₄

(a)

(i)

What is meant by the pole of a magnet?

(ii)

Draw the magnetic lines of force around a bar magnet.

(b)

List four post harvest activities required in the preservation of maize.

(c)

Describe the processes that take place between pollination and seed formation in flowering plants.

(d)

Distinguish beteween:

(i)

an atom and an ion;

(ii)

neutralization and esterification.

Show Solution

(a)

(i)

The pole of a magnet is the part of the magnet where the magnetic force is strongest.

The pole of a magnet is the region of a magnet toward which the lines of magnetic induction converge or diverge.

The pole of a magnet is either of the two ends of a magnet at which the field of the magnet is most intense.

(ii)

The magnetic lines of force around a bar magnet

Note: The direction of arrows is from North to South

(b)

Post harvest activities required in the preservation of maize

1. Dehusking
2. Threshing/shelling
3. Drying
4. Winnowing
5. Treatment with recommended chemical
6. Bagging
7. Storage

(c)

Processes that take place between pollination and seed formation in flowering plants

1. Pollen grain absorbs water/germinates
2. Pollen grain develops/grows into a pollen tube
3. The pollen tube grows through the style and down the wall of the ovary carrying two nuclei (or tube nucleus and generative nucleus)
4. The generative nucleus divides to form two male gametes
5. The pollen tube passes through the micropyle of the ovule into the embryo sac where the tip dissolves setting free male gametes
6. One male fuses/unites with the egg nucleus/ovum to form the zygote which develops into the embryo of the future seed
7. However, the other male gamete fuses with the polar nucleus (or endosperm nucleus) and the fertilized ovule becomes a seed

(d)

(i)

Distinction between an atom and an ion

Atom	Ion
Electrically neutral particle	Charged particle
Smallest (indivisible) unit of matter	An atom with an electric charge
The number of protons and electrons are the same	The number of protons and electrons are not the same
Take part in a chemical reaction	Cannot take part in a chemical reaction/Attract each other by electrostatic force

(ii)

Distinction between neutralization and esterification

Neutralization	Esterification
Reaction between an acid and a base (to give salt and water only)	Reaction between an organic acid and an alkanol
Is exothermic	Is endothermic
Is fast/not catalysed	Is slow/requires a catalyst
Produces salt and watr only	Produces ester and water
Is not reversible	Is reversible

(a)

Define each of the following terms as associated with reproduction in humans:

(i)

copulation;

(ii)

ejaculation;

(iii)

ovulation;

(iv)

menstruation.

(b)

Name the type of oxide formed when each of the following elements reacts with oxygen:

(i)

sulphur;

(ii)

sodium;

(iii)

zinc.

(c)

(i)

What is short-sightedness?

(ii)

Describe briefly how short-sightedness could be corrected?

(d)

Give four reasons why it is important to keep records during crop production.

Show Solution

(a)

(i)

Copulation is the insertion of the penis into the vagina of a female.

(ii)

Ejaculation is the release/discharge of semen into the vagina during mating

(iii)

Ovulation is the release of ripe/mature ovum/egg by the ovaries.

(iv)

Menstruation is the periodic/monthly discharge of blood from the vagina.

(b)

(i)

Type of oxide formed when sulphur reacts with oxygen

Acidic oxide

(ii)

Type of oxide formed when sodium reacts with oxygen

Basic oxide

(iii)

Type of oxide formed when zinc reacts with oxygen

Amphoteric oxide

(c)

(i)

Short-sightedness is a defect of the eye that causes distant objects not to be seen clearly whereas near objects can be seen (clearly).

(ii)

How short-sightedness could be corrected

It can be corrected by the use of concave/diverging lens so as to focus rays from distant objects onto the retina.

(d)

Reasons why it is important to keep records during crop production

1. To determine whether the enterprise is making profits or loss/to show income and expenditure
2. Records show how much tax to pay
3. It helps the farmer to plan/budget for the future/making management decisions
4. It helps to know total investment made into the farm business
5. It helps the farmer to obtain loans
6. To determine the amount of yield/productivity/sales made
7. It gives information on decision made earlier
8. It gives information on the past/cropping history/know when crops will be harvested
9. It provides reasons why things worked or other things did not work
10. To avoid repeating mistakes
11. To measure progress in crop production
12. To know when next to apply pest or disease control chemical
13. For educating new generation of farmers
14. To know when next to apply fertilizer
15. For the farmer to know his/her weaknesses

(a)

Calculate the mass of quicklime produced when 10 g of limestone is heated.

[Ca = 40; C = 12; O = 16]

The equation for the reaction is: CaCO₃ → CaO + CO₂

(b)

(i)

List three emissions of radioactivity.

(ii)

State the charge of each of the emissions listed in (i).

(c)

(i)

List three sources of organic matter in the soil.

(ii)

State two advantages of tilling as a method of land preparation in crop production.

(d)

Name four blood vessels associated with the human heart.

Show Solution

(a)

CaCO₃ → CaO + CO₂

Method I

Molar mass of CaCO₃ = 40 + 12 + 16 x 3 = 100 g

Molar mass of CaO = 40 + 16 = 56 g

100 g of CaCO₃ = 56 g of CaO

10 g of CaCO₃ = $\frac{56 x 10}{100}$ = 5.6 g of CaO

Method II

Mole = $\frac{Mass}{Molar Mass}$

Mass of CaCO₃ = 10 g

Molar mass of CaCO₃ = 100 g/mol

Mole of CaCO₃ = $\frac{10}{100}$ = 0.1 mol

From the reaction, 1 mole of CaCO₃ produces 1 mole of CaO

0.1 mol of CaCO₃ will produce 0.1 mol of CaO

Mass = Mole x Molar Mass

Mole of CaO = 0.1 mol

Molar mass of CaO = 56 g/mol

Mass of CaO = 0.1 mol x 56 g/mol = 5.6 g

(b)

(i)

Emissions of radioactivity

1. Alpha particles/ α particles
2. Beta particles/ β particles
3. Gamma/ γ rays
4. Energy

(ii)

Charges on the emissions

1. Alpha particles/ α particles → + 2
2. Beta particles/ β particles → -1
3. Gamma/ γ rays → no charge/0
4. Energy → no charge/0

(c)

(i)

Sources of organic matter in the soil

1. Dead/decaying plants/animals or other organisms
2. Cell/tissue of soil organisms/living organisms
3. Substances synthesized by soil organisms
4. Faeces/animal droppings/manure/compost

(ii)

Advantages of tilling as a method of land preparation in crop production

1. It helps to mix organic matter with the soil/it improves the fertility of the soil
2. It loosens soil for easy root penetration and development
3. For easy percolation/infiltration of water
4. It aids aeration
5. It helps to control weeds better

(d)

Names of blood vessels associated with the human heart

1. The aorta
2. The pulmonary artery
3. The pulmonary vein
4. Superior vena cava
5. Inferior vena cava

PRACTICAL QUESTIONS

The diagrams below illustrate three different types of specialized cells, labelled A, B and C, found in humans.

Study the illustrations carefully and answer the questions that follow.

(a)

(i)

Identify each of the cells labelled A, B and C.

(ii)

Name each of the parts labelled I, II, III, IV, V, VI, VII and VIII.

(iii)

State one function of each of the parts labelled I, III, VI and VII.

(b)

(i)

State the location of each of the cells labelled A, B and C in the human body.

(ii)

State the importance of each of the cells labelled A, B and C.

Show Solution

The diagrams below illustrate an electrical circuit used to investigate a scientific law. The rheostat is adjusted to vary the current and voltage in the circuit.

Fig 2(a) and Fig 2(b) below illustrate ammeter readings I = I₁, I₂, I₃, I₄ and I₅ and the corresponding voltmeter readings V = V₁, V₂, V₃, V₄ and V₅, respectively when the key is closed.

(a)

Read and record the ammeter readings I = I₁, I₂, I₃, I₄ and I₅ in Table 1 below.

(b)

Read and record the voltmeter readings V = V₁, V₂, V₃, V₄ and V₅ in Table 1 below.

Table 1

I/A	V/V
I₁ =	V₁ =
I₂ =	V₂ =
I₃ =	V₃ =
I₄ =	V₄ =
I₅ =	V₅ =

(c)

Plot a graph with V on the vertical axis and I on the horizontal axis.

(d)

Determine the slope of the graph.

(e)

State the significance of the slope.

(f)

(i)

Using the graph, determine the voltage in the circuit when the current I = 0.82 A.

(ii)

Using the graph, determine the current in the circuit when the voltage V= 5 V.

(g)

Name the scientific law investigated.

Show Solution

Note:

The interval for the current is 0.25 and there are 5 divisions.

Value of each division = $\frac{0.25}{5}$ = 0.05

The interval for the voltage is 1 and there are 5 divisions.

Value of each division = $\frac{1}{5}$ = 0.2

I/A	V/V
I₁ = 0.5	V₁ = 2.0
I₂ = 0.5 + 3 x 0.05 = 0.65	V₂ = 2.0 + 3 x 0.2 = 2.6
I₃ = 0.75 + 3 x 0.05 = 0.90	V₃ = 3.0 + 3 x 0.2 = 3.6
I₄ = 1.00	V₄ = 4.0
I₅ = 1.50	V₅ = 6.0

(c)

Notes:

Value per grid = $\frac{Interval}{Number of grids per interval}$

Value per grid for voltage = $\frac{0.5}{10}$ = 0.05

Value per grid for current = $\frac{0.2}{10}$ = 0.02

Number of grids = $\frac{Value}{Value per grid}$

Number of grids for current 0.65 A = $\frac{0.65}{0.02}$ = 32.5 (Between 32 and 33 grids from 0)

Number of grids for voltage 2.6 V = $\frac{2.6}{0.05}$ = 52 from 0

Number of grids for voltage 3.6 V = $\frac{3.6}{0.05}$ = 72 from 0

(d)

Slope = $\frac{Change in the Y - axis}{Change in the X - axis}$ = $\frac{Y_{2} - Y_{1}}{X_{2} - X_{1}}$

From the points A(0.5, 2.0) and B(1.5, 6.0)

Slope = $\frac{6.0 - 2.0}{1.5 - 0.5}$ = 4 Ω

(e)

The slope represents the resistance (in the circuit).

(f)

(i)

When the current I = 0.82 A, voltage = 3.3 V

Note:

Value per grid for voltage = 0.05

Corresponding voltage = 66 grids = 66 x 0.05 = 3.3 V

(ii)

When the voltage V= 5 V, current = 1.24 A

Note:

Value per grid for current = 0.02

Corresponding current = 62 grids = 62 x 0.02 = 1.24 A

(g)

The scientific law investigated is Ohms law.

The diagram below illustrates two management systems, labelled A and B, practiced in chicken production.

Study the diagram carefully and answer the questions that follow.

(a)

Identify the management system being practiced in each of A and B.

(b)

Name the type of housing used in each of the systems labelled A and B.

(c)

Name each of the parts labeled I, II, III and IV.

(d)

Name the type of chicken being kept in the system labelled B.

(e)

State three advantages that the system labelled A has over the system labelled B.

(f)

Give two reasons for recommending the system labelled B to a commercial poultry farmer.

Show Solution

The diagram below is an illustration of a set up used to separate a mixture of kerosene and water.

Study the diagram carefully and answer the questions that follow.

(a)

Name the method used in separating the mixture.

(b)

Identify each of the parts labelled I, II, III, IV, V and VI.

(c)

State the function of each of the parts labelled I and V.

(d)

State one physical property of the liquids that would enable the separation to occur.

(e)

Name the components of two other liquid-liquid mixtures that could be separated using this method.

Show Solution

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