CBSE Class 8 Science NSO Olympiad MCQs with Answers Set N

Question. Which of the following statements are true?
I. When a batsman hits a cricket ball with his bat, the force applied by the batsman is muscular force.
II. In an electric bell, the hammer strikes the gong due to electrostatic force.
III. During dry weather, hair tend to attract the comb while combing, this is due to magnetic force of attraction.
IV. Walking on ice is difficult because of lack of frictional force.
A. I and II only
B. I and IV only
C. II, III and IV only
D. I, II and IV only
Answer : B

Question. Match column I with column II and select the correct option from the codes given below.
        Column I                        Column II
P. String vibration                I. Tabla
Q. Membrane vibration       II. Bicycle bell
R. Vibration of air               III. Guitar
S. Vibration of plate           IV. Flute
     P       Q      R      S
A. III      I        IV      II
B. IV      III      II       I
C. III      IV      II       I
D. II       I        IV      III
Answer : A

Question. In a large commercial complex there are four ways to reach the main road. One of the paths has loose soil, the second is laid with a polished granite, the third is laid with bricks and the fourth has cemented gravel surface. It is raining heavily and Suman wants to reach the main road. The path on which she is least likely to slip is
A. Loose soil
B. Bricks
C. Polished granite
D. Cemented gravel.
Answer : D

Question. The diagram shows two mercury barometers, one filled with a partial vacuum and the other filled with air. What happens to the height of mercury, h when these two barometers are taken to a mountain top?

            Air                     Partial vacuum
A. Decreases                Decreases
B. Decreases                Increases
C. Increases                 Increases
D. Remains same        Decreases
Answer : A

Question. A car travelling normally towards a cliff at a speed of 50 m s–1, sounds its horn when it is 0.7 km away. Taking the speed of sound to be 300 m s–1 in air, find the time taken for the driver to hear its echo.
A. 0.04 s
B. 4.0 s
C. 4.7 s
D. 28.0 s
Answer : B

Question. A pith ball makes contact with, and is then repelled by a highly charged sphere as shown in the diagram. 
Which of the following will happen when an earthed metal plate is brought close to, but not touching, the pith ball?

A. The ball will be repelled to the far side of the dome.
B. The ball will be repelled so that it makes contact with dome.
C. The ball will be attracted to the plate, make contact, and be neutralised.
D. The ball will be attracted to the plate, make contact, and then be repelled.
Answer : C

Question. The pressure on the tyres of a sedan car is P. The contact surface of each tyre with the floor is A. Find the new contact surface of each tyre when air is released from the tyre and the pressure of the car is reduced to 0.75 P.
A. 1.25 A
B. 1.33 A
C. 1.67 A
D. 4.00 A
Answer : B

Question. A plane mirror is inclined at 40° to floor as shown in figure.

An incident ray parallel to the floor strikes the mirror and a reflected ray is formed.
If the angle of inclination is increased to 50° without changing the direction of the ray, then what is the change in angle between the incident ray and the reflected ray?
A. 5°
B. 10°
C. 20°
D. 40°
Answer : C

Question. A thin convex lens is placed on a plane mirror. A pen is adjusted vertically until its image is seen to be at the same position when viewed from the top as shown.
Given that f is the focal length of the lens, what is the distance between the pen and the optical centre of the lens?

A. 0.5 f
B. f
C. 2 f
D. 4 f
Answer : C

Question. Suppose a new planet is discovered which revolves around the Sun (i.e., it is a part of our solar system).
What is its time period if its orbit lies between Saturn and Uranus?
A. Less than that of Uranus
B. More than that of Uranus
C. Equal to that of Uranus or Saturn
D. Less than that of Saturn
Answer : A

Question. A person throws a ball vertically upwards standing on the surface of earth. Same person throws same ball with same force vertically upwards standing on the surface of moon. Then,
A. The ball thrown from the moon will keep going up and never come back
B. The ball thrown from earth will attain more height than the ball thrown from the moon
C. In both the cases, balls will attain same heights
D. The ball thrown from the moon will attain more height than the ball thrown from the earth.
Answer : D

Question. Read the given statements and select the correct option.
Statement 1: LEDs are increasingly being used for lighting.
Statement 2: LED light sources consume less electricity and have longer lifetime than light bulbs and fluorescent tubes.
A. Both statement 1 and statement 2 are true and statement 2 is the correct explanation of statement 1.
B. Both statement 1 and statement 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. Statement 1 is false but statement 2 is true.
Answer : A

Question. Ram has a sitar. The string is plucked in the middle first and a sound is produced. Again, the middle of the string is pressed and plucked at one-fourth of the length with the same force and an another sound is produced. Which of the following statements is correct?
A. Sound produced in first case is louder.
B. Sound produced in first case has higher pitch.
C. Sound produced in second case is louder.
D. Sound produced in second case has higher pitch.
Answer : D

Question. A group of acrobats stack themselves as shown. Given that all the acrobats have same weight, which acrobat(s) must be the strongest?

A. 1 and 2
B. 3
C. 4 and 5
D. 6, 7 and 8
Answer : B

Question. A wooden table of mass 100 kg is lying on a floor.
A man pushes the table with a force of 100 N and another man tends to stop the table with a force of 200 N as shown in the figure. If the friction between the floor and table is 80 N, then 100 N 100 kg 200 N

A. The table will move towards right with 100 N force
B. The table will move towards left with 20 N force
C. The table will remain at rest
D. The table will move towards right with 20 N force.
Answer : B

Question. The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m s^–1. The driver sees in his rear view mirror the image of a truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be
A. 1 m s^–1
B. 2 m s^–1
C. 4 m s^–1
D. 8 m s^–1
Answer : B

Question. What principle is used in a newton spring balance?
A. The mass of an object depends on its density.
B. The mass of an object depends on the gravity pulling it.
C. The weight of an object is directly proportional to its mass.
D. The extension of the spring is directly proportional to the weight pulling it, and weight depends upon mass.
Answer : D

Question. Match column I with column II and select the correct option from the codes given below.
   Column I                   Column II
P. Bulb                          I. Insulator
Q. Electroplating          II. Conductor
R. Pure water              III. Heating effect of current
S. Salt solution            IV. Chemical effect of current
     P           Q          R          S
A. III          II           IV          I
B. III          IV          I            II
C. I            III          IV          II
D. IV          III          II           I
Answer : B

Question. A force of 12 N acts on a block P and block Q of masses 2 kg and 4 kg respectively as shown. Given that the floor is smooth, find the force on the string between  blocks P and Q.

A. 2 N
B. 4 N
C. 8 N
D. 12 N
Answer : C

Question. Which of the following statements are correct?
I. The flame of a kerosene lamp gives off light because carbon particles produced due to incomplete combustion of kerosene burn with a glow.
II. A yellow flame indicates complete combustion.
III. A yellow flame deposits black soot on cooking utensils.
IV. All combustible substances produce flame.
V. Petrol is a better fuel than kerosene.
A. I and II only
B. I, III and V only
C. III and V only
D. III, IV and V only
Answer : B

Question. A few materials are listed in the box.
(i) Nylon (ii) Acrylic (iii) Terylene
(iv) Cotton (v) Wool (vi) Melamine
(vii) PET
Which of the following represents a correct statement about these materials?
A. (ii), (iv) and (v) are natural polymers.
B. (ii) is a good substitute for wool and (iii) is a good substitute for silk.
C. (vii) is a thermosetting plastic while (vi) is a thermoplastic.
D. (iii) and (vii) are polyesters while (i) is a polyamide
Answer : D

Question. Ms. Rashmita, a science teacher has set up an experiment as shown in the figure.

Which of the following represent the correct observations?
(i) Both the metal strips dissolve in beaker II.
(ii) Colour change is observed in beaker I.
(iii) No reaction takes place in beaker III.
(iv) Fe strip will dissolve faster in beaker I.
(v) Reaction occurs in beaker III but no colour change is observed.
A. (iii) and (iv) only
B. (i) and (iii) only
C. (ii) and (v) only
D. None of these
Answer : B

Question. Calorific values of a few fuels are given in the table.
Fuel                                P      Q      R         S      T
Calorific value (kJ/g)  6-8    50   150    17-22   45
Fuels P, Q, R, S and T can be best represented by
A. Wood, kerosene, hydrogen, cowdung cakes and petrol
B. Cowdung cakes, methane, hydrogen, wood and petrol
C. Hydrogen, petrol, kerosene, cowdung cakes and wood
D. None of these.
Answer : B

Question. Nitika, a class 8 student performed a few experiments to study the reactivity of metals. She summarised her observations in the given table.

Answer : C

Question. Rohit took a burning candle and covered it with a glass chimney as shown in figure I. He took another burning candle and slid a thin tin plate with a hole in the middle just below the flame and above the melted wax as shown in figure II. Then, he took the third candle and covered it with a glass chimney which was kept on the wooden blocks as shown in figure III.

Which of the following observations is correct?
A. Smoke is produced in candle III due to less supply of air.
B. Candles I and III burn freely.
C. Tin plate conducts more heat towards the wick and hence, candle II becomes brighter.
D. The flame flickers and produces smoke in candle I.
Answer : D

Question. The given table represents the properties and uses of a few plastics

The plastics represented incorrectly are
A. I and IV only
B. I and III only
C. II and III only
D. I, III and V only.
Answer : B

Question. The given figure represents contents of a matchstick

Answer : B

Question. Soham studied burning characteristics of a few fibres and summarised his observations in the given table

Fibres I, II, III, IV and V could be respectively
A. Polyester, silk, nylon, acrylic and wool
B. Acrylic, wool, cotton, nylon and silk
C. Nylon, silk, polyester, wool and cotton
D. Nylon, cotton, polyester, rayon and silk.
Answer : D

Question. Read the given passage and fill in the blanks by selecting an appropriate option.
Non-metals find wide applications in industries. For example i is used in electrodes, ii is used in welding metals, iii is used to make antiseptic creams while iv is used as a preservative due to its inert nature.

Answer : C

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

A. P – (iii), Q – (iv), R – (i), S – (v), T – (ii)
B. P – (iv), Q – (v), R – (ii), S – (iii), T – (i)
C. P – (iv), Q – (i), R – (ii), S – (iii), T – (v)
D. P – (iii), Q – (ii), R – (v), S – (iv), T – (i)
Answer : C

Question. Select the option that correctly identifies the given species as extinct (P), critically endangered (Q) and vulnerable (R) according to IUCN Red List.

Answer : C

Question. Names of a few protected areas are given below.
Kanha National Park, Dachigam National Park,
Keoladeo National Park, Jim Corbett National Park,
Ranthambore National Park, Dudhwa National Park,
Periyar National Park, Pin Valley National Park,
Gangotri National Park
How many of these are tiger reserves?
A. 6
B. 8
C. 4
D. 5
Answer : D

Question. Refer to the given Venn diagram

Which of the following can be placed at X ?
(i) Manufacture of different antibiotics
(ii) Preparing yogurt
(iii) Fermentation of sugar to get alcohol
(iv) Manufacture of vitamin B complex tablets
(v) Decomposition of organic waste and ensuring nutrient recycling in ecosystem
(vi) Causing diseases in plants and animals
A. (ii), (iii) and (vi)
B. (i), (ii), (v) and (vi)
C. (i), (iii), (iv), (v) and (vi)
D. (ii), (iii), (iv) and (v)
Answer : C

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

A. (a) - (iii), (b) - (v), (c) - (iv), (d) - (i), (e) - (ii)
B. (a) - (iv), (b) - (v), (c) - (iii), (d) - (i), (e) - (ii)
C. (a) - (iii), (b) - (v), (c) - (i), (d) - (iv), (e) - (ii)
D. (a) - (iv), (b) - (v), (c) - (ii), (d) - (i), (e) - (iii)
Answer : A

Question. Select the incorrect difference(s) between National park and Sanctuary.

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

Question. A large forest area was destroyed by forest fire and remained without any vegetation for a long time. It finally got converted to a desert.
Which of the following graphs correctly depicts the changes in various parameters of that area over a period of time from the point of deforestation to desertification ?
Key:
— Groundwater level
— Mean annual temperature
— Top soil

Answer : C

Question. Read the given paragraph.
Organelle X is abundantly present in glandular cells and is actively involved in glycosylation of proteins synthesised in organelle Y. Both organelles are involved in the formation of organelle Z that brings about cell autolysis.
Identify organelles X, Y and Z and select the correct option regarding them.
A. Organelles X and Z are bound by double membranes whereas organelle Y is bound by single membrane.
B. Organelle Z takes part in disposal of cell debris and also provides nourishment during starvation by hydrolysing organic food stored in cells.
C. Organelles X and Y are abundantly found in mammalian red blood cells whereas organelle Z is found only in plant cells.
D. Organelle Y provides large surface area for attachment of single membrane bound organelle which is often referred to as protein factory.
Answer : B

Question. Refer to the given figure and select the correct option regarding it.

A. The given pregnancy is dangerous for the mother as the Fallopian tube might rupture as the fetus enlarges.
B. The walls of Fallopian tubes are not suited to thickening and vascularisation unlike the uterine wall hence, the developing fetus may not receive sufficient nutrients and oxygen.
C. The given case is a normal pregnancy where zygote first implants in Fallopian tube and later in the third trimester it detaches and migrates to uterus for implantation in uterine wall and further development.
D. Both A and B
Answer : D

Question. Refer to the given Venn diagram.

Select the correct option regarding organisms P, Q and R.
A. P could be toucan whereas Q could be black mamba.
B. P could be Anguilla whereas R could be Necturus.
C. R could be salmon whereas Q could be Pteropus.
D. P could be Struthio whereas Q could be Casuarius.
Answer : C

Question. The given graph shows changes in the levels of gonadal hormones X and Y in two normal persons, respectively over their lifetime.

Select the correct option regarding this.
A. X causes development of breasts whereas Y causes broadening of pelvic region during puberty in adolescents.
B. Gland that secretes X also secretes large number of motile gametes every month whereas gland secreting Y usually secretes one non-motile gamete every month.
C. If persons producing hormones X and Y respectively would have married each other and produced babies then only person producing Y would have been responsible for determining the sex of babies.
D. Person secreting hormone X produces gametes only during the period between menarche and menopause however person secreting hormone Y can produce gametes right from puberty till the end of life.
Answer : B

Question. Refer to the given flow chart.

Identify hormones X and Y and select the correct option regarding them.
A. Glands secreting hormone Y are located on the posterior surface of glands secreting hormone X.
B. Myxoedema is caused by hyposecretion of a hormone secreted by gland that also secretes hormone Y.
C. Both hormones X and Y are secreted by same endocrine gland but are antagonistic to each other in functioning.
D. Hyposecretion of hormone Y leads to osteoporosis as more calcium is drawn from bones to raise blood calcium level.
Answer : A

Question. The given diagram represents a village.
The waste material from residential area and factories is dumped into the river stream that passes through the village.

Which line in the graph correctly shows the change in the population of aquatic fish when they swim downstream from points P to Q?
A. I
B. II
C. III
D. IV
Answer : C

Question. Naina placed two different cultures of unicellular organisms, Q and R, into two identical beakers. She allowed both organisms to grow in the beakers and recorded the amount of area they had grown every 10 minutes. She then tabulated the results as follows:

Based on the results in the table, which of the following conclusions could be made ?
A. Organism Q multiplied itself at every interval of ten minutes. 
B. Organisms Q and R are sexually reproducing organisms.
C. Organism R multiplied itself at every interval of forty minutes.
D. At the end of an hour, organism R had grown faster than organism Q.
Answer : A

Question. Refer to the given dichotomous key and select the incorrect option regarding it.
I. (a) It is a prokaryotic microorganism. – Go to II
(b) It is a eukaryotic microorganism. – Go to III
II. (a) It causes a disease in plants. – P
(b) It causes a disease in humans. – Q
III. (a) It possesses chlorophyll. – R
(b) It lacks chlorophyll. – Go to IV
IV. (a) It is used in production of an antibiotic. – S
(b) It causes kala azar in humans. – T
A. P could be Xanthomonas that causes citrus canker in plants whereas Q could be Clostridium that causes tetanus in humans.
B. R could be Chlorella whereas S could be Streptomyces.
C. S could be Penicillium whereas T could be Leishmania.
D. Q could be Mycobacterium that causes tuberculosis in humans whereas S could be Aspergillus.
Answer : B

Question. The given pie chart depicts the percentage population of five animals in a grassland ecosystem that are related to each other in a food chain.

If heavy pesticides are sprayed on plants in this area then select the option that correctly depicts the ascending order of pesticide concentration in living tissues of animals at different trophic levels.
A. P < Q < R < S < T
B. T < S < R < Q < P
C. R < T < P < Q < S
D. S < T < R < Q < P
Answer : B

ACHIEVERS SECTION

Question. Refer to the given table and select the correct option regarding P, Q, R, S and T.

Answer : B

Question. Read the given paragraph.
Sameer is a farmer who lives in Rajasthan. In the past few years, he was only sowing maize crop in his field.
But with each passing year the crop yield went down gradually.
What could be the probable reason for this (P) ? Also suggest a suitable solution to this problem (Q).

Answer : A

Question. The given figure represents destructive distillation of coal

Study the figure carefully and choose the incorrect statement(s).
I. The residue left behind after destructive distillation of coal is a better fuel than coal and produces no smoke.
II. X is used for the manufacture of producer gas and nitrogenous fertilisers.
III. Y is almost a pure form of carbon and is used to reduce metal oxides to get metals.
IV. Z on fractional distillation yields many organic compounds which are used to make pesticides, explosives, perfumes etc.
V. The process is carried out by heating coal strongly to about 1000°C in the presence of air.
A. I, III and IV only
B. II, III, IV and V only
C. I only
D. All of these
Answer : B

Direction (Q. No. a and b): Refer to the given passage and answer the following questions.
An experiment is conducted by a student to check the conductivity of potato and the set-up is shown here.

Question. Which of the following will be the observation made by the student if the switch is closed and circuit is left unattended for one hour?
I. Bulb will start glowing as soon as the switch is closed.
II. Bulb will not glow throughout the experiment.
III. Bulb will glow after an hour of the switch is closed.
IV. A yellowish blue spot will appear around negative electrode.
V. A greenish blue spot will appear around positive electrode.
A. I and V only
B. III, IV and V only
C. II and V only
D. I and IV only
Answer : A

Question. What happens to the compass needle when the switch is closed?
A. The compass needle will point towards the right.
B. The compass needle will point towards the left.
C. The compass needle will not deflect.
D. The compass needle will point downwards
Answer : B