CBSE Class 8 Science NSO Olympiad MCQs with Answers Set L

SCIENCE

Question. Five blocks, B1, B2, B3, B4 and B5 of different masses are connected by four identical strings S1, S2, S3 and S4 as shown in the figure. They are pulled by a steadily increasing force F. Which of the following strings is most likely to break?

A. S₁
B. S₂
C. S₃
D. S₄
Answer : A

Question. Three blocks, P, Q and R are balanced on a beam with the pivot at the midpoint.
The correct order of blocks in terms of increasing mass, is

A. P < Q < R
B. R < P < Q
C. P < R < Q
D. Q < P < R
Answer : C

Question. A source of light O is located at a distance of 8 cm from a plane mirror. The reflected ray O' is detected 2 cm from the mirror at a vertical displacement of 12 cm.
The point of reflection is at a distance of

A. 6.0 cm from X
B. 7.2 cm from X
C. 2.4 cm from Y
D. 3.6 cm from Y
Answer : C

Question. Solve the following riddle by identifying X, Y, Z.
X : I am a cooking ingredient and a conductor of electricity.
Y : I am used in an electric circuit when a weak current flows through it.
Z : I am coated on iron bridges to protect it from corrosion and formation of rust.
            X                     Y               Z
A. Lemon juice         LED       Chromium
B. Lemon juice        CFL        Gold
C. Vinegar               LED        Zinc
D. Vinegar               CFL        Silver
Answer : C

Question. The diagram shows a bubble at the bottom of a pool.
Assuming that the temperature of the pool is constant throughout the water, which of the following describes the change of the pressure and the density of air in the bubble as it rises to the surface?

    Pressure             Density
A. Increase              Increase
B. Increase              Decrease
C. Decrease            Increase
D. Decrease            Decrease
Answer : D

Question. A beam of light from a torch is aimed at an arrangement of four plane mirrors. Which diagram correctly shows the path that the light beam follows?

Answer : A

Question. Consider the given cases. 
I : A ball moves vertically upwards after being kicked by a boy.
II : The ball falls vertically downwards after reaching the maximum height.
Name the forces responsible for the motion of ball in the two cases.
              I                                  II 
A. Muscular force              No force
B. Muscular force              Gravitational force
C. Frictional force              No force
D. Frictional force              Gravitational force
Answer : B

Question. Which of the following statements is incorrect?
A. Pressure in a liquid increases with depth, but at the same depth it is equal in all directions.
B. The air above presses down on us with a force equal to that exerted by a mass of 1 kg, on every cm².
C. Atmospheric pressure increases as height above sea level increases.
D. Pressure is greater when area of contact is smaller.
Answer : C

Question. The distance of Alpha Centauri from Earth is about 4.3 light years. The time taken by the light to reach Earth from Alpha Centauri is about
A. 1.35 × 106 s
B. 1.35 × 107 s
C. 1.35 × 108 s
D. 1.35 × 109 s
Answer : C

Question. An object vibrates 7200 times in 8 minutes. A girl standing close to the object hears
A. A sound of frequency (7200/8)Hz
B. A sound of frequency (7200×8/60)Hz
C. A sound of frequency (7200×60/8)Hz
D. No sound.
Answer : D

Question. Match the column I with column II and select the correct option from the given codes.

A. P - 1, Q - 3, R - 2, S - 4
B. P - 3, Q - 1, R - 4, S - 2
C. P - 4, Q - 2, R - 3, S - 1
D. P - 2, Q - 4, R - 1, S - 3
Answer : D

Question. The loudness of sound coming from murmur in a quite library is about 30 decibel while that from a car horn is about 120 decibel. The ratio of the amplitudes of vibrations producing these sounds is
A. 1 : 1
B. 1 : 2
C. 1 : 4
D. 1 : 16
Answer : B

Question. The given figure shows a small positively charged sphere O, kept in between two larger positively charged spheres X and Y which are fixed.

In which direction will the sphere O move?
A. Up
B. Down
C. Left
D. Right
Answer : B

Question. Read the given statements carefully.
(i) Lighting a matchstick.
(ii) Tying shoe laces.
(iii) Applying the brakes on a cycle.
(iv) Writing on the blackboard with a chalk.
(v) Treaded tyres of vehicles.
In which of the following cases is the friction helpful?
A. (i) and (v) only
B. (i), (iv) and (v) only
C. (ii), (iv) and (v) only
D. (i), (ii), (iii), (iv) and (v)
Answer : D

Question. In which of the following will the compass needle show deflection?

Answer : B

Question. Read the given statements and select the correct option.
Statement 1 : Parallel rays are incident on a surface but the reflected rays are not parallel. This type of reflection is called diffused reflection.
Statement 2 : Diffused reflection occurs due to failure of laws of reflection.
A. Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1.
B. Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1.
C. Statement 1 is true and statement 2 is false.
D. Both statements 1 and 2 are false.
Answer : C

Question. In a game of tug-of-war, two teams P and Q pull at a rope in opposite directions.

Forces applied by the members of team P are 125 N, 137 N and 209 N whereas that by the members of team Q are 129 N, 186 N and 146 N. Then
A. The rope will move towards team P
B. The rope will move towards team Q
C. The rope will not move at all
D. Movement of rope cannot be predicted.
Answer : A

Question. Which of the following statements are correct about planet Venus?
(i) It rotates from west to east while the Earth rotates from east to west.
(ii) It shows phases just like the Moon.
(iii) It appears in the eastern sky before sunrise and in the western sky just after sunset.
(iv) It has no satellite of its own.
(v) It is the second brightest star in the night sky.
A. (i) and (iii) only
B. (i), (iii) and (v) only
C. (ii), (iii) and (iv) only
D. (i), (ii), (iii), (iv) and (v)
Answer : C

Question. A special bathroom mat keeps Rohan safe from slipping and falling in his bathroom. It does this by
A. Reducing the amount of friction between his feet and the bathroom floor
B. Keeping the bathroom floor free from moss
C. Helping Rohan's feet stay dry while he takes his bath
D. Creating more friction under Rohan's feet, as he steps on the mat.
Answer : D

Question. Match the column I with column II and select the correct option from the given codes.
     Column I                Column II
(p) Rayon          (i) Does not get wrinkled easily
(q) Bakelite       (ii) Used to make electrical switches
(r) PVC             (iii) Artificial silk
(s) Polyester     (iv) Thermoplastic
A. (p) - (iv), (q) - (iii), (r) - (i), (s) - (ii)
B. (p) - (iii), (q) - (iv), (r) - (ii), (s) - (i)
C. (p) - (iii), (q) - (ii), (r) - (iv), (s) - (i)
D. (p) - (ii), (q) - (i), (r) - (iii), (s) - (iv)
Answer : C

Question. Most of the non-metals
A. are lustrous
B. are malleable and ductile
C. react with oxygen to produce acidic oxides
D. react with water and acids to produce hydrogen gas.
Answer : C

Question. Which of the following statements is incorrect?
A. Coke is used in place of coal tar for metalling the roads.
B. Petrochemicals are used in the manufacture of detergents, fibres, polythene, etc.
C. Naphthalene balls are obtained from coal tar.
D. Coke is used in the manufacture of steel and in the extraction of many metals.
Answer : A

Question. Fill in the blanks by choosing an appropriate option.
Matchstick head contains (1) and (2). The rubbing surface has powdered (3) and a little (4) . When the matchstick is struck against the rubbing surface, some (4) gets converted into (5) . This immediately reacts with (2) in the matchstick head to produce enough heat to ignite (1) and start the combustion.

Answer : A

Question. Ankita, a class 8 student arranged the given experimental set-up to study the reactivity of three different metals X, Y and Z.

Metals X, Y and Z are respectively
A. Cu, Al and Fe
B. Ag, Fe and Zn
C. Fe, Cu and Al
D. Al, Cu and Fe
Answer : C

Question. Look at the given figure showing petroleum and natural gas deposits.

The layer containing petroleum oil and gas is above that of water because
A. Oil and gas are heavier than water and do not mix with it.
B. Oil and gas are lighter than water and get mixed with it.
C. Water is lighter than oil and gas and does not mix with them.
D. Oil and gas are lighter than water and do not mix with it.
Answer : D

Question. Values of ignition temperatures of different substances are listed in the given table.

Increasing order of the inflammability of the given substances is
A. I < IV < II < III
B. III < II < IV < I
C. IV < I < III < II
D. II < III < I < IV
Answer : B

Question. Which of the following statements about thermosetting plastics are correct?
1. Bakelite and melamine are thermosetting plastics.
2. They get deformed easily on heating and can be moulded easily to make toys, combs, etc.
3. Melamine resists fire and can tolerate heat better than other plastics
4. When moulded once, they cannot be softened by heating.
A. 1, 2 and 4 only
B. 1 and 2 only
C. 1, 3 and 4 only
D. All of these
Answer : C

Question. Read the following statements carefully.
W : I am very reactive and catch fire if exposed to air. To prevent this, I am stored in water.
X : I am a good conductor of heat and acquire a reddish-brown coating on exposure to moist air.
Y : I am soft and have dull appearance. I form acids on reacting with oxygen and water.
Z : I am malleable, ductile and acquire a dull green coating on exposure to moist air.
Identify W, X, Y and Z.

Answer : B

Question. Geeta marked the statements about fire extinguishers, given by her teacher as true or false.

Which of these statements are marked incorrectly by her?
A. 1 and 3 only
B. 2 and 4 only
C. 1 and 4 only
D. None of these
Answer : A

Question. Mrs. Nitika, a science teacher has collected few fuel samples in different glass jars and put labels on them with their calorific values (in kJ/kg).

She asked her students to arrange these fuels in the increasing order of fuel efficiency. The correct order is
A. 4 < 2 < 3 < 1
B. 1 < 3 < 2 < 4
C. 2 < 4 < 1 < 3
D. 3 < 1 < 4 < 2
Answer : C

Question. Identify I, II and III in the given flow chart and select the correct option.

A. I - Cryopreservation, II - Biosphere reserve, III - National park,
B I - Gene bank, II - Wildlife sanctuary, III - Home garden
C. I - Biosphere reserve, II - National park, III - Wildlife sanctuary
D. I - Biosphere reserve, II - Gene bank, III - Cryopreservation
Answer : D

Direction : Read the following passage and answer questions a and b.
Microbial diseases that can spread from an infected person to a healthy person through air, water, food or physical contact are called X. There are some insects and animals that are Y of disease causing microbes. Housefly is one example.

Question a. Which of the following can be an example of X in the passage?
A. Typhoid
B. Allergy
C. Asthma
D. Rickets
Answer : A

Question b. Which of the following is an incorrect pair of animal that works as Y and the disease it is associated with?
A. Rat - Plague
B. Cockroach - Hepatitis B
C. Culex - Filaria
D. Anopheles - Malaria
Answer : B

Question. Which of the following statements is/are correct regarding mixed cropping?
(i) Mechanical harvesting becomes easier.
(ii) It increases biodiversity.
(iii) It removes some nutrients specifically from the crop field.
(iv) Outbreaks of pests and diseases can spread very rapidly.
(v) The crops with different maturation times are grown together.
A. (i) and (ii) only
B. (ii) and (v) only
C. (iii) and (iv) only
D. (iii), (iv) and (v) only
Answer : B

Question. Which graph shows changes that occur in a river after being polluted by sewage?

Answer : A

Question. Read the given statements and select the correct option.
Statement 1 : The chemical substances produced by microorganisms which in low concentration are antagonistic to the growth of other microorganisms are called as antibiotics.
Statement 2 : A preparation of a dead or attenuated pathogen, which when injected into a healthy person, provides immunity against a specific disease or number of diseases, is called a vaccine.
A. Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1.
B. Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1.
C. Statement 1 is true but statement 2 is false.
D. Both statements 1 and 2 are false.
Answer : B

Question. Select the option that correctly fills the blanks in any two of the given statements.
(i) ______ refers to the plants found in a particular area.
(ii) ______ species are those which are going to be extinct in near term future.
(iii) The lion tailed macaque is included in ______ species in red data book.
(iv) A place rich in ______ species is called hotspot.
A. (i) Fauna, (ii) Endangered
B. (iii) Endangered, (iv) Endemic
C. (i) Flora, (iii) Vulnerable
D. (ii) Rare, (iv) Endangered
Answer : B

Question. Select the correct differences between National Park and Sanctuary.

A. (i) and (iii)
B. (i) and (iv)
C. (ii) and (iii)
D. (ii) and (iv)
Answer : B

Question. The given figure shows a typical animal cell with its components labelled as ‘a – j’.

Identify the labelled components and select the incorrect statement regarding them.
A. The organelles ‘e’, ‘h’, ‘g’ and ‘i’ are membranebound structures which function in close  coordination with one another.
B. ‘f’ organelle is responsible for the synthesis of fats inside the cells and it stores Ca²⁺ for release during muscle contraction.
C. ‘a’ and ‘b’ are selectively permeable membranes.
D. ‘j’ is the site for protein synthesis. It allows hereditary message from ‘d’ to get translated into proteins.
Answer : B

Question. A student examined a particular plant cell through its various stages of growth. After making various measurements, he realised that the increase in cell size was largely due to enlargement of the central vacuole rather than an increase in the amount of cytoplasm. Why might this be an advantageous strategy for the cell?
A. Enlarging the cytoplasm would make the cell less turgid.
B. Enlarging the vacuole would make it unnecessary for the cell wall to stretch.
C. Enlarging the vacuole would minimise any lowering of the surface area - volume ratio of the cytoplasm.
D. All of these
Answer : C

Question. The given figure represents various endocrine glands present in human body. Identify these glands and select the correct option.

A. Low secretions of gland (i) can result in dwarfism.
B. Gland (iv) controls development of puberty characters in an individual.
C. Glands (ii) and (iii) work in close coordination to maintain blood sugar level.
D. Gland (v) secretes hormones that help regulate the rate of metabolism.
Answer : A

Question. Plant X is a vascular and invasive plant species that grows densely over the surface of a lake at a very high rate, due to pollution in water. It has been linked to oxygen depletion of the water, in spite of the fact that it is photosynthetic.
Which of the following accounts for this contradiction?
A. While being photosynthetic, X consumes oxygen at a faster rate than it releases the same, because of its high rate of growth.
B. Because X is highly invasive, it incorporates a large quantity of oxygen in its biomass.
C. When X dies, the bacteria that decompose its dead body consume the oxygen dissolved in water and grow rapidly.
D. None of these
Answer : C

Question. The given graph shows estimated amount of different pollutants present in emission from a factory. Which of the following is a likely outcome of this?

A. Global warming and ozone layer depletion
B. Acid rain
C. Thermal pollution
D. All of these
Answer : D

Question. Refer to the given Venn diagram. Which among the following would most likely be X?

A. Acid rain
B. Vehicular exhausts
C. Oil spills
D. Agricultural runoff water
Answer : B

Question. Match the following agricultural tasks with their respective implements and select the correct option.
Agricultural tasks           Implements
(a) Tilling                        (i) Combine
(b) Sowing                     (ii) Trowel
(c) Irrigation                   (iii) Seed drill
(d) Weeding                  (iv) Plough
(e) Harvesting               (v) Sprinkler
A. (a)-(v), (b)-(ii), (c)-(iv), (d)-(i), (e)-(iii)
B. (a)-(iv), (b)-(iii), (c)-(v), (d)-(ii), (e)-(i)
C. (a)-(iii), (b)-(iv), (c)-(v), (d)-(i), (e)-(ii)
D. (a)-(ii), (b)-(iii), (c)-(v), (d)-(iv), (e)-(i)
Answer : B

ACHIEVERS SECTION

Direction : Read the given paragraph carefully and answer the questions a and b.

Refer to the given figure.

A thin bar is hinged to the wall. It remains in equilibrium.
Five forces acting on the bar are shown in the figure.

Question a. What is the moment due to the force Y?
A. 0 N m
B. 10 N m
C. 20 N m
D. Data insufficient
Answer : A

Question b. What are the values of forces X and Z respectively?
A. 15 N, 5 N
B. 10 N, 10 N
C. 20 N, 0 N
D. Data insufficient.
Answer : B

Question. Petroleum contains a large number of components having different boiling points. They are separated by fractional distillation as shown in the given figure :

The boiling point range of few fractions of petroleum is given in the table.

Identify P, Q, R and S

Answer : C

Question. Refer to the given figures which show three different types of fission. Select the option which correctly matches them with the organism in which they occur

Answer : C

Question. Read the given paragraph with few blanks in it.
During the process of cloning Dolly, a cell was collected from the ______ of a ______ ewe and an egg was collected from ______ ewe and was enucleated. The nucleus from the mammary gland cell was taken, and inserted into this enucleated egg and the egg (______) was implanted into the ______ ewe which gave birth to Dolly after due time.
Now select the option that will correctly fill the blanks in the above paragraph.
A. Ovarian follicle, Finn Dorsett, Scottish blackface, haploid, Finn Dorsett
B. Ovarian follicle, Scottish blackface, Finn Dorsett, diploid, Finn Dorsett
C. Mammary gland, Finn Dorsett, Scottish blackface, diploid, Scottish blackface.
D. Mammary gland, Finn Dorsett, Scottish blackface, haploid, Finn Dorsett
Answer : C