O/L 2021 Science Smart MCQ paper paperEnglish medium

1. To which of the following organizational level does the human heart belong?

(1)

cell.

(2)

tissue.

(3)

organ.

(4)

system.

2. The hydrocarbons contained in LP gas as it's major components are,

(1)

methane and ethene.

(2)

propane and butene.

(3)

butene and pentane.

(4)

propane and pentane.

3. What is the unit of the amount of the work?

(1)

Kg m s-1

(2)

Kg m s-2

(3)

Kg m-1 s-1

(4)

Kg m2 s-2

4. Which of the following is not a characteristic of cardiac muscle tissue?

(1)

cells being mononuclear.

(2)

occurrence of intercalated discs.

(3)

cells being branched.

(4)

acting voluntarily.

5. A seed observed by a student during a field study is shown in the diagram. This seed is dispersed by,

(1)

animals.

(2)

water.

(3)

wind.

(4)

explosion.

6. Which of the following quantity increases uniformly in an object moving with a constant acceleration?

(1)

distance.

(2)

displacement.

(3)

velocity.

(4)

retardation.

7. which of the following is equal in given K and Ca atoms?

(1)

number of electrons.

(2)

number of neutrons.

(3)

sum of the number of electrons and protons.

(4)

sum of the number of protons and neutrons.

8. Which property of water causes water to be used as a cooling agent to remove excessive heat generated in an automobile engine?

(1)

having a high specific heat capacity.

(2)

having a high boiling point.

(3)

being a colourless liquid.

(4)

having a high density.

9. In the process of digestion of food, bile necessary for the emulsification of lipids is produced in the,

(1)

gall bladder.

(2)

liver.

(3)

duodenum.

(4)

pancreas.

10. what is the essential element for the production of thyroxine hormone in the thyroid gland?

(1)

sodium.

(2)

phosphorus.

(3)

calcium.

(4)

iodine.

11.

(1)

585g

(2)

58.5g

(3)

5.85g

(4)

0.585g

12. R and S respectively represent,

(1)

uterus and vagina.

(2)

uterus and fallopian tube.

(3)

ovary and vagina.

(4)

ovary and fallopian tube.

13. An ovum fertilizes with a sperm in,

(1)

(2)

(3)

(4)

14. The image of a real object produced by a convex mirror is always,

(1)

real and smaller than the object.

(2)

real and larger than the object.

(3)

virtual and smaller than the object.

(4)

virtual and larger than the object.

15. what is the correct increasing order of pH of given four solutions

(1)

(2)

(3)

(4)

16.

(1)

(2)

(3)

(4)

17.

(1)

urea possesses the properties of the constituent elements.

(2)

a molecule of urea has 2 carbon atoms.

(3)

a molecule of urea has 4 hydrogen atoms.

(4)

the total number of atoms in a urea molecule is seven.

18. Which option contain only the components that are found in the glomerular filtrate but not in urine of a healthy person

(1)

glucose, amino acid.

(2)

water, glucose.

(3)

urea, amino acids.

(4)

water, urea.

19. A jack fruit of mass 10Kg is falling freely from a height of 5m of a jack tree. What is the velocity acquired by the fruit when it touches the ground? [acceleration due to gravity is 10m s-2 . resume that the resistance of the air is negligibly small]

(1)

(2)

(3)

(4)

20. Select the correct answer regarding the circulation of blood in humans.

(1)

always arteries contained oxyganated blood.

(2)

when circulated once through the body, blood goes twice through the lungs.

(3)

left ventricle act as the pump of systamic blood circulation.

(4)

always veins circulates blood away from the heart.

21. A few ways of connecting four resistors of equal magnitude are given. out f them which one has the lowest equivalent resistance?

(1)

(2)

(20

(3)

(4)

22. consider the following organs, A-skin B-kidneys C-pancreas out of these , those that contribute to maintain homoeostasis of the body is/are

(1)

only A

(2)

only A and B

(3)

only B and C

(4)

all A,B and C

23. The graph P and Q respectively indicates how the body temperature of two organisms P and Q varies with the temperature of the environment. the organism P and Q respectively can be,

(1)

ox and bat.

(2)

fowl and tortoise.

(3)

elephant and duck.

(4)

frog and thilapia.

24. In which order does the brightness of the bulb decreases in the circuit A,B and C

(1)

A>B>C

(2)

A>C>B

(3)

B>C>A

(4)

C>A>B

25. Some information regarding an element are as follows. * has several allotropic forms. * one allotropic form conduct electricity. this element is,

(1)

carbon.

(2)

oxygen.

(3)

sulphur.

(4)

iron.

26. Some functions of the human brain are given below. A-reception of senses. B-maintaining the balance of the body. C-controlling the rate of heart beat. out of the above cerebellum controls,

(1)

only A

(2)

only B

(3)

only Aand B

(4)

only B and C

27. Consider the following statements A-the rate of reaction increases when the temperature increases B-the kinetic energy of reactant particles increases when temperature increases of these,

(1)

both statements A and B are true.

(2)

statement A is true and statement B is false.

(3)

both statements A and B are false.

(4)

statement A is false and statement B is true.

28. Which of the following phenomena cannot be explained by the archimedes principle?

(1)

a ship cruising in the sea sinking more when entering a river.

(2)

a ballon filled with helium gas moving upwards through air.

(3)

floating of sunk orange seeds in a glass of orange juice when dissolving sugar.

(4)

lifting a large mass by a hydraulic jack by applying a small force.

29. The diagram shows a cross section of cylindrical concreate ring kept on a flight of steps. indicates as A,B,C and D are four points at which force can be applied by a man to roll it to the upper level. what is the point at which force can be applied on the cylinder in a suitable direction to roll it up with a lowest force?

(1)

(2)

(3)

(4)

30. when thin iron wool is heated, it instantly burns. but though an iron nail till red hot, it does not undergo a considerable change. what conclusion can be drawn from these observations?

(1)

iron wool acts as a catalyst.

(2)

iron wool and iron nail undergo reactions different from each other.

(3)

the composition of iron nail and iron wool is different from each other.

(4)

the rate of reaction depends on the physical nature of the reactants.

31. In,2011, the number of elephants in Sri Lanka was 5879. what is the most suitable bio spherical organizational level to denominate that number of elephants?

(1)

species.

(2)

population.

(3)

community.

(4)

eco-system.

32. select the correct option that regards to a npn transistor,

(1)

(2)

(3)

(4)

33. The situation of transverse wave travelling on the surface of water at a certain moment is shown in the figure. the amplitude and wavelength of this wave respectively are,

(1)

4cm and 5cm

(2)

4cm and 10cm

(3)

5cm and 4cm

(4)

8cm and 10cm

34. Which of the following statement is false about electroplating of iron?

(1)

an aqueous solution of a compound of a metal that electroplated should be the electrolyte.

(2)

the electrolyte should be high concentration for quality electroplating.

(3)

iron should be made thecathode of the electrolytic cell.

(4)

the current used should be a direct current.

35. A conical flask containing aqueous hydrochloric acid is kept on a sensitive balance. pieces of limestone were added to it in excess. which of the following graph indicates how the balance reading varies against time after the addition of limestone?

(1)

(2)

(3)

(4)

36.

(1)

(2)

(3)

(4)

37. for the energy obtaining method of which house is only a non-renewable energy source used?

(1)

(2)

(3)

(4)

38. Which house use the lighting devices that largely contribute to pollute soil and water when improperly disposed to the environment?

(1)

A and C

(2)

A and D

(3)

B and C

(4)

B and D

39. Which house use the cooking equipment that minimally contributes to pollute air inside the house?

(1)

(2)

(3)

(4)

40. What is the house that has taken most practical solutions to the electricity and fuel crisis?

(1)

(2)

(3)

(4)