CBSE Class 8 Science NSO Olympiad MCQs with Answers Set O

SCIENCE

Question. The given figure shows a small positively charged sphere O, kept near 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 : D

Question. Read the given statements carefully.
(i) Gymnasts apply some coarse substance on their hands.
(ii) Tying shoe laces.
(iii) Applying the brakes on a car.
(iv) Writing on the blackboard with a chalk.
In which of the following cases is the friction helpful?
A. (i) and (ii) only
B. (i), (ii) and (iii) only
C. (ii), (iii) and (iv) only
D. (i), (ii), (iii) and (iv)
Answer : D

Question. Which of the following statements is/are false?
I. Pressure in a liquid increases with depth, but at the given depth it is equal in all directions.
II. The pressure due to a fluid is independent of cross-sectional area of the fluid.
III. Atmospheric pressure increases as height above sea level increases.
IV. Upthrust on a floating block in a liquid is equal to the weight of liquid displaced by the block.
A. I and II only
B. III only
C. I, II and IV only
D. III and IV only
Answer : B

Question. The displacement-time graph of two notes I and II are shown. Which note has a higher frequency and which note has a lower wavelength?

       Higher              Lower
    frequency       wavelength
A.      I                         I
B.      I                         II
C.      II                        I
D.      II                        II
Answer : D

Question. A charged rod is held close to one side of a metal ball and the other side is earthed. Which diagram correctly shows the charge distribution?

Answer : D

Question. There are four circuit arrangements.

The compass needle(s) will show deflection in circuit(s)
A. I only
B. II and III only
C. II only
D. II and IV only
Answer : C

Question. Read the given statements and select the correct option.
Statement 1 : When a guitar string is plucked lightly then it produces a feeble sound.
Statement 2 : Loudness of sound does not depend on the amplitude of vibrations of a vibrating object.
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 : C

Question. An earthquake of magnitude 6 on Richter scale is how many times more destructive than an earthquake of magnitude 4?
A. 100
B. 1000
C. 1500
D. 2000
Answer : B

Question. The diagram shows two plane mirrors inclined at an angle of 50º to each other.
A ray is incidenton mirror 1, then the deviation x (shown in the figure) of ray after two reflections is

A. 50°
B. 100°
C. 120°
D. 150°
Answer : B

Question. The wavelength of a certain sound wave is 110 m long.
Given that the speed of sound in air is approximately 330 m s^–1 and the audible range of a normal person is 20 Hz to 20000 Hz. An observer who is standing 220 m away from the source of this sound wave hears
A. A loud and high pitch sound
B. A soft and low pitch sound
C. Sound but its properties cannot be determined.
D. Nothing.
Answer : D

Question. Richa conducted an experiment as shown in the figure to investigate how the height of the ramp affects the amount of force needed to move a wooden block up the ramp.

Which of the following variables must be kept the same to ensure that her experiment is fair?
I. Number of bricks
II. Material of the ramp
III. Size of the wooden block
IV. Mass of the wooden block
A. I, II and III only
B. I, III and IV only
C. II, III and IV only
D. I, II, III and IV
Answer : C

Question. An object is accelerating under the influence of a force F₁ on a frictionless surface. A while later, an opposing force F₂ of the same magnitude acts on it as shown in the figure. What will happen to the object?

A. The object will slow down.
B. The object will move at constant velocity.
C. The object will come to rest immediately after the opposing force acts on it.
D. The object will move in the opposite direction.
Answer : B

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

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

Question. The following figure shows the displacement of a particle within 40 ns. What will be the displacement of the particle when t = 70 ns?

A. –2 mm
B. 0 mm
C. 1 mm
D. 2 mm
Answer : A

Question. Read the given statements and select the correct option.
Statement 1 : The conductivity of an electrolyte is very low as compared to a metal at room temperature.
Statement 2 : The density of free ions in electrolyte is much smaller than density of free electrons in metals.
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 : A

Question. Which of the following statements is/are true?
I. A constellation has only 5-10 stars.
II. Aryabhatta was the first Indian satellite.
III. Artificial satellites are used for weather forecasting and remote sensing only.
IV. Venus is the brightest planet in the night sky.
A. II only
B. II and III only
C. II and IV only
D. IV only
Answer : C

Question. Match column I and column II and select the correct option from the given codes.
    Column I             Column II
P. Electroscope        (i) Conductor
Q. Copper                (ii) Lightning rods
R. Spikes                 (iii) Ozone
S. Lightning             (iv) Charge
A. P-(iv), Q-(i), R-(ii), S-(iii)
B. P-(ii), Q-(iii), R-(iv), S-(i)
C. P-(iii), Q-(iv), R-(i), S-(ii)
D. P-(iii), Q-(i), R-(ii), S-(iv)
Answer : A

Question. Man X is standing in front of a plane mirror while man Y is running towards him from behind. If the man Y is running at a speed of 2 m s–1, how many metres nearer does the man Y seem to be away from man X after 5 seconds?

A. 30 m
B. 15 m
C. 10 m
D. 20 m
Answer : C

Question. Two identical balls are dropped separately into two identical tubes. One of the tubes is filled with air and the other has its air pumped out with a vacuum pump.
Which of the following observation(s) is/are true?
I. Both the balls will reach the bottom of the tube with same speed.
II. Both the balls will reach the bottom of the tube with different speed.
III. Both the balls will reach the bottom of the tube at the same time.
A. II only
B. I and II only
C. II and III only
D. None of these
Answer : A

Question. Select the incorrect statements.
I. Coal is a mixture of chemical substances containing carbon, hydrogen, oxygen and small amount of nitrogen and sulphur.
II. Inexhaustible natural resources cannot be replenished continually.
III. When coal is heated in the absence of air, carbon monoxide is produced which is a poisonous gas.
IV. Coal is used as a source of energy in various industries like cement, paper, steel etc.
A. I and III only
B. II and III only
C. II and IV only
D. I, II, III and IV
Answer : B

Question. Match the columns and select the correct option from the given codes.

A. P-(ii)-(b), Q-(iii)-(c), R-(iv)-(a), S-(i)-(d)
B. P-(i)-(d), Q-(iii)-(c), R-(iv)-(a), S-(ii)-(b)
C. P-(iii)-(a), Q-(i)-(b), R-(ii)-(d), S-(iv)-(c)
D. P-(ii)-(d), Q-(i)-(b), R-(iii)-(a), S-(iv)-(c)
Answer : C

Question. Shaheen tested the water absorption capacities of different fibres. She cut equal sized squares from three different fabrics and weighed them. She then placed each fabric square into a beaker containing water and again weighed the fabrics after 15 minutes. All her observations are summarised in the given table.

Fabrics W, X and Y could be respectively
A. Cotton, polyester, nylon
B. Cotton, nylon, wool
C. Wool, cotton, nylon
D. Nylon, cotton and wool.
Answer : D

Question. Match the columns and select the correct option from the given codes.

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

Question. Calorific values of four fuels P, Q, R, S and T is in the order, T > R > Q > S > P.
P, Q, R, S and T could be respectively
A. LPG, petrol, wood, cow dung cakes and hydrogen
B. Petrol, hydrogen, LPG, cow dung cakes and wood
C. Cow dung cakes, kerosene, LPG, wood and hydrogen
D. Petrol, LPG, hydrogen, wood and cow dung cakes.
Answer : C

Question. A few processes are listed in the box.
(i) Respiration
(ii) Burning of LPG in kitchen
(iii) Burning of candle
(iv) Rusting
(v) Burning of phosphorus
(vi) Burning of fire crackers
(vii) Burning of sodium
Which of the following is correct regarding these processes?
A. (i) and (iv) are examples of spontaneous combustion
B. (ii) and (iii) are examples of rapid combustion.
C. (vi) and (vii) are examples of slow combustion.
D. (i) and (v) are examples of slow combustion.
Answer : B

Question. Observe the given experimental set-ups carefully.
In figure (I), a thin long copper wire is introduced into the non-luminous zone of a candle flame; in figure (II), a clear glass slide is introduced into the luminous zone while in figure (III), one end of a glass tube is introduced into the dark zone of a candle flame.

Which of the following is incorrect regarding these experiments?
A. Copper wire in figure I will become red hot because outermost zone is the hottest part of flame.
B. Blackish ring will be formed on glass plate in figure II because of unburnt carbon particles in the middle zone of candle flame.
C. A flame is formed at the end of glass tube in figure III due to unburnt wax vapours in the innermost zone of candle flame.
D. None of these
Answer : D

Question. Select the correct statements.
I. Teflon is used to make the windscreen wipers of cars because it has low friction.
II. Nylon is used to make ropes for rock climbing because it is very strong.
III. Bakelite is used for making electric plugs, switches etc. as it is a good conductor.
IV. Dusters made of nylon or other synthetic materials are good for use in kitchen as they are soft.
V. Blended fabrics are long lasting as they contain only synthetic fibres.
A. III and V only
B. I and II only
C. III and IV only
D. IV and V only
Answer : B

Question. Select the correct statements.
I. Dry powder of chemicals like sodium bicarbonate or potassium bicarbonate when released near the fire, gives off CO₂.
II. Water should be used to extinguish fire caused by cooking oil.
III. When CO₂ stored in cylinders is sprayed on fire, it cuts off the supply of oxygen as well as brings down the temperature of the fuel.
IV. Sand can be used to extinguish fire caused by electrical equipments.
A. I and II only
B. II and IV only
C. I, III and IV only
D. I, II, III and IV
Answer : C

Question. Select the incorrect match. 
        Gas                        Main components
A. Coal gas             –     Hydrogen + Methane
B. Natural gas         –     Methane
C. Petroleum gas    –     Methane + Propane
D. Biogas                –     Methane
Answer : C

Question. Which of the following represents the correct decreasing order of boiling points of the given liquids?
A. Paraffin wax > Diesel > Kerosene > Petrol
B. Diesel > Kerosene > Petrol > Paraffin wax
C. Kerosene > Petrol > Paraffin wax > Diesel
D. Petrol > Paraffin wax > Diesel > Kerosene
Answer : A

Question. Identify the agricultural implement given in the figure and select the correct statement regarding it.
A. It is used for separating grain from the harvested crop.
B. It is used for separating grain from the chaff.
C. It is used for sowing seeds in the soil at an equal distance.
D. It is used for loosening and turning the soil for making it breathable for plants.
Answer : B

Question. Refer to the given Venn diagram and select the incorrect statement regarding P-S.

A. P could be Bacillus anthracis that causes anthrax. 
B. Q could be Vibrio cholerae that causes cholera in humans.
C. R could be Chlamydomonas that is distributed widely in fresh water.
D. S could be Giardia that causes intestinal infection in humans.
Answer : C

Question. Identify processes X and Y from the given statements and select the option that correctly identifies the microorganisms involved in them respectively.
X : Conversion of complex organic compounds into ammonia
Y : Conversion of nitrates in soil to free nitrogen
           X                                  Y
A. Aspergillus                    Bacillus
B. Micrococcus                 Thiobacillus
C. Pseudomonas              Nitrocystis
D. Bacillus                         Pseudomonas
Answer : D

Question. 'X' is a protected land area reserved for the conservation of wild animals and birds. Poaching and capturing of animals is strictly prohibited here. However, activities like harvesting of timber and collection of minor forest products is allowed. X could be
A. Mudumalai Wildlife Sanctuary, Tamil Nadu
B. Kanha National Park, Madhya Pradesh
C. Pachmarhi Biosphere Reserve, Uttar Pradesh
D. National Zoological Park, New Delhi.
Answer : A

Question. Consider the following statements and select the option which correctly identifies true (T) and false (F) ones.
(i) Reproductive life of woman lasts from menarche to menopause.
(ii) In females, the uterus wall thickens to receive the embryo.
(iii) Estrogen is released by testes at the onset of puberty.
(iv) Hormones secreted by adrenal glands stimulate testes and ovaries to produce their hormones.
    (i)    (ii)    (iii)    (iv)
A. T      F       T       F
B. T      F       F       F
C. T     T        F       F
D. T     T        F       T
   Answer : C

Question. What path does a sperm take from where it is produced to where it would fertilise an egg?
A. Testis→ Sperm duct→Urethra→Vagina→Oviduct
B. Testis→Urethra→Sperm duct→Vagina→Cervix
C. Prostate→Testis→Sperm duct→Vagina→Oviduct
D. Scrotum→Testis→Sperm duct→Uterus→Vagina
Answer : A

Question. Which of the following options are not consequences of deforestation?
I. Reduced rainfall
II. Change in climate
III. Overgrazing by animals
IV. Volcanic eruptions
V. Imbalance of atmospheric gases
A. II, III and IV only
B. III, IV and V only
C. I and V only
D. III and IV only
Answer : D

Question. Refer to the given Venn diagram and select the option that correctly identifies cell organelle.

(i) Centrosome
(ii) Cell wall
(iii) Mitochondria
(iv) Golgi complex
(v) Chloroplast
A. (iii) and (iv) only
B. (ii), (iv) and (v) only
C. (i), (iii) and (v) only
D. (i), (ii) and (iii) only
Answer : A

Question. Crop plants may be attacked by pests which affect the crop production. Fungi are such type of pests which cause diseases like Leaf cell P Leucocyte
A. Smut of wheat
B. Citrus canker
C. Blight of potato
D. Both A and C.
Answer : D

Question. Refer to the given figures of male and female reproductive systems.

Select the incorrect statement regarding them.
A. Both M and Z are primary sex organs in males and females respectively.
B. L helps to deliver male gamete in the Y of females.
C. Gamete released by M fertilises female gamete in X.
D. Both B and C
Answer : C

Question. Untreated sewage is discharged into a river from nearby homes. Within few weeks, the number of fish in the river significantly falls. Which of the following could not have caused this phenomenon?
A. Algal blooms
B. Excessive bacterial growth
C. Overcrowding due to increasing fish populations
D. Increased levels of nitrates and phosphates
Answer : C

Question. Geetanjali is a student of class VIII. One day her elder sister wrote the given statements regarding a cell organelle.
I. Bounded by single membrane
II. Filled with watery fluid
III. Helps in osmoregulation
IV. Stores metabolic by-products
She is referring to
A. Plastid
B. Vacuole
C. Mitochondria
D. Endoplasmic reticulum.
Answer : B

Question. Read the given paragraph where few words have been italicised. Make changes (wherever necessary) and select the incorrect option.
Dolly was developed from a cell taken from mammary gland of Scottish black face ewe and unfertilised egg cell of Finn Dorsett sheep. Both the cells were fused after removing the plasma membrane from the unfertilised egg cell. Embryo was then implanted into the uterus of the sheep from which unfertilised egg was taken. It developed into baby sheep Dolly.
A. Mammary gland should not be changed as it is correctly mentioned.
B. Position of Scottish blackface ewe and Finn Dorsett sheep should be interchanged.
C. Plasma membrane must be changed to nucleus.
D. None of these
Answer : D

Question. The given graphs show the change in global sea levels with respect to time.
Which of these graphs correctly depicts that deforestation has taken place over time?

Answer : B

Question. Read the given statements about gaseous pollutants P, Q, R and S of air and select the option which correctly identifies them.
(i) P could be a gas produced due to biological degradation of organic matter present in sewage.
(ii) Q could be a gas that on combining with haemoglobin forms carboxyhaemoglobin.
(iii) R could be a gas that is released from refrigerators and air conditioners.
(iv) S and sulphur dioxide could be gases that are produced upon burning fossil fuels like petrol, coal, etc., and can cause acid rain

Answer : D

ACHIEVERS SECTION

Direction (Q. No. a and b) : Read the given passage and answer the following questions.

A cuboid rests on the floor. Data of the cuboid and some other parameters are given here

Question a. By rotating the cuboid, what is the minimum pressure it can exert on the floor?
A. 7500 Pa
B. 10000 Pa
C. 5000 Pa
D. 20000 Pa
Answer : C

Question b. By rotating the cuboid, what is the maximum pressure it can exert on the floor?
A. 3000 Pa
B. 7500 Pa
C. 5000 Pa
D. 10000 Pa
Answer : D

Question. Five beakers are arranged as shown in the figure

Study the given set-up carefully and select the correct statements.
I. Reaction will take place in beakers (ii) and (v).
II. A colour change will take place in beakers (i) and (v).
III. A white deposition will be formed on copper turnings in beaker (iv).
IV. A brown deposition will be formed on iron filings in beaker (i) and on zinc granules in beaker (v).
V. Reaction will take place in all the beakers but colour change will be observed only in beakers (i) and (iii).
A. I and IV only
B. II and IV only
C. III and IV only
D. II, III and V only
Answer : B

Question. Refer to the given flow chart and select the correct option regarding X, Y and Z.

Answer : C

Question. Given below is a list of organelles present in a cell. 
1. Cell wall 2. Chloroplast
3. Ribosome 4. Vacuoles
5. Mitochondria 6. Peroxisome
7. Cell membrane 8. Nucleus
Identify the option that correctly matches description of cell to its missing cell organelle

    L     M    N    O
A. 6     2     3     1
B. 3     8     6     7
C. 5     7     4     6
D. 2     4     7     8
Answer : B