CBSE Class 8 Science NSO Olympiad MCQs with Answers Set E

LOGICAL REASONING

Question. If each vowel in the word MOUNTAIN is replaced by the next letter in the English alphabet and each consonant is replaced by the previous letter in the English alphabet, then which of the following will be the fourth letter to the left of seventh letter from the left end?
A. T
B. V
C. N
D. P
Answer : B

Question. Select a figure from the options which will continue the same series as established by the Problem Figures.

Answer : B

Question. Study the following arrangement carefully and answer the question given below.
B A 5 D % R I * F H 6 # V 9 $ 3 E 7 G 1 ÷ 2 M K X 8 U F W Z N
What should come in place of the (?) in the following series based on the above arrangement?
ADI F69 37÷ ?
A. 2KU
B. MXU
C. MXF
D. XUM
Answer : C

Question. Two rows of numbers are given. The resultant number in each row is to be worked out separately based on the following rules. The operations on numbers progress from left to right. Rules :
(i) If a two-digit odd number is followed by a prime number, the first number is to be multiplied by the prime number.
(ii) If an even number is followed by another even number, the first number is to be divided by the second number.
(iii) If an odd number is followed by a composite odd number, the first number is to be added to the second number.
(iv) If an even number which is a multiple of 5 is followed by another number which is again a multiple of 5, the second number is to be subtracted from the first number.
(v) If a number which is a perfect square is followed by another number which is also a perfect square, then the square roots of the two numbers is to be multiplied.
64       25     25
88         8       n
If n is the resultant of the first row, what is the resultant of the second row?
A. 24
B. 36
C. 28
D. 26
Answer : D

Question. In which of the following options, Fig. (X) is exactly embedded as one of its part?

Answer : D

Question. Select the option in which specified components of the Fig. (X) are found?

Answer : C

Question. Find the missing number, if a certain rule is followed row-wise or column-wise.

A. 15
B. 18
C. 19
D. 20
Answer : B

Question. Which of the following options most closely resembles the water image of given combination of letters and numbers?

Answer : A

Question. P, Q, R, S, T, V and W are sitting around a circle facing the centre. R is third to the right of V, who is second to the right of P. T is second to the left of Q, who is second to the left of W. V is sitting between S and W.
Who is sitting between T and V?
A. W
B. R
C. S
D. Can't be determined
Answer : C

Question. Read the following information carefully.
'A ★ B' means 'A multiplied by B'.
'A @ B' means 'A minus B'.
'A $ B' means 'A plus B'.
'A # B' means 'A divided by B'.
Mohit donates 7% of his monthly salary R to charity and spends ` 3,000 per month on his house rent. What is the amount left with him out of his monthly salary after excluding house rent and charity amount?
A. R @ (3000 @ 7 ★ 100#R)
B. R @ (7 ★ R # 100 @ 3000)
C. R @ (R ★ 7 # 100 $ 3000)
D. None of these
Answer : C

SCIENCE

Question. A simple pendulum, oscillating with time period T, is shown in the figure. Time taken by the bob to move from A to C is t1 and from C to O is t₂. Then

A. Motion of the bob is uniform with T = 2(t₁ + t₂)
B. Motion of the bob is uniform with T = 4(t₁ + t₂)
C. Motion of the bob is non uniform with T = 2(t₁ + t₂)
D. Motion of the bob is non-uniform with T = 4(t₁ + t₂).
Answer : D

Question. A box is being pushed horizontally along a rough surface and a constant acceleration is achieved. If the push is stopped, the box will
A. Slow down and finally stop
B. Continue to move at constant speed
C. Continue to accelerate at a lower rate
D. Stop immediately.
Answer : A

Question. A block of mass 4 kg and dimensions 10 cm × 20 cm × 30 cm rests on the floor. If g = 10 m s^–2, then the maximum pressure the block can exert on the floor is
A. 2000 N m^–2
B. 1000 N m^–2
C. 4000 N m^–2
D. 1333 N m^–2
Answer : A

Question. Which of the following statements are true about both light and sound ?
(i) They are forms of energy.
(ii) They can be converted into other forms of energy.
(iii) They undergo reflection.
A. (i) and (ii) only
B. (ii) and (iii) only
C. (i) and (iii) only
D. (i), (ii) and (iii)
Answer : D

Question. Which of the following options correctly represents the relative positions of the Sun (S), Moon (M) and Earth (E) on the day of full moon and new moon?
    Full Moon           New Moon
A. MES                     MSE
B. SME                     ESM
C. SEM                     SME
D. ESM                     EMS
Answer : C

Question. What is the use of cooking oil in frying a fish in terms of heat transfer?
A. To increase rate of heat transfer to the fish via radiation.
B. To increase rate of heat transfer to the fish via convection.
C. To increase rate of heat transfer to the fish via conduction.
D. To increase rate of heat transfer to the fish via evaporation.
Answer : C

Question. The given figure shows a set-up for testing conduction of electricity in different liquids. Pick out the group of liquids for which the bulb will not glow.

A. Milk, Lemon juice, Tap water, Honey
B. Vinegar, Tap water, Kerosene, Lemon juice
C. Honey, Kerosene, Vegetable oil, Distilled water
D. Vegetable oil, Distilled water, Vinegar, Kerosene
Answer : C

Question. Why does a horse need to pull harder during the first few steps in pulling the cart?
A. Static friction is greater than sliding friction.
B. Sliding friction is greater than rolling friction.
C. No frictional force acts after the cart comes in motion.
D. Air friction is greater during first few steps of motion.
Answer : A

Question. Which of the following statements are correct?
(i) Venus is the hottest planet of the solar system.
(ii) Jupiter is called the red planet as it has a large red spot on its surface.
(iii) Revolving speed of Mercury is fastest of all planets.
(iv) Mars has no natural satellites of its own.
(v) Saturn is the least dense planet among all planets.
A. (ii) and (iii) only
B. (ii), (iv) and (v) only
C. (i), (iii) and (v) only
D. (i), (ii), (iv) and (v) only
Answer : C

Question. Two uncharged conducting spheres are placed in contact with each other. Which of the following diagrams best represents the charge distribution when a negatively charged rod is placed near one of them?

Answer : C

Question. The intensity of sound wave gets reduced by 10% on passing through a slab. The total reduction in intensity on passing through three consecutive slabs is
A. 30%
B. 70%
C. 27.1%
D. 72.9%
Answer : C

Question. The given table shows the melting and boiling points of four elements

Which element is in liquid state at 311°F?
A. E4
B. E3
C. E2
D. E1
Answer : A

Question. The given diagram shows a girl standing at a position X in front of a plane mirror, at a distance of x m from the mirror.
When she moves y m away to a new position Y, the distance between the girl and her image increases by 8 m.
What is the value of y ?

A. 2 m
B. 4 m
C. 8 m
D. Data insufficient
Answer : B

Question. Read the given statements and select the correct option.
Statement 1 : Smoke goes upwards.
Statement 2 : The warm air is lighter than the cold air.
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. The given figure shows a circuit which contains three identical lamps and two switches.
Which of the following statements is correct regarding the given circuit?

A. When switch 2 is closed and switch 1 is open, all the three lamps glow.
B. When switch 2 is closed and switch 1 is open, only lamp 1 and lamp 3 glow.
C. When switch 1 is closed and switch 2 is open, only lamp 2 glows.
D. When both switch 1 and switch 2 are closed, all the three lamps glow.
Answer : B

Question. Read the given statements and select the correct option.
Statement 1 : The gas produced on burning sulphur in air is dissolved in water to form an acidic solution.
Statement 2 : The process represents a physical change as the substance formed is composed of same elements sulphur, oxygen and hydrogen.
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. Match the Column I with Column II and select the correct option from the given codes.

Answer : C

Question. Fill in the blanks left in the classification of the fossil fuels.

Answer : B

Question. When a copper vessel is exposed to moist air for long, it acquires a dull green coating. The reaction can be represented as

W, X, Y and Z are respectively
A. N₂, CO₂, O₂ and CuO
B. H₂O, N₂, CO₂ and O₂
C. H₂O, CO₂, O₂ and CuCO₃
D. H₂O, CO₂, O₂ and CuO.
Answer : C

Question. Fill in the blanks by choosing an appropriate option.
Acids are compounds that contain (i) atoms. Sulphuric acid is one such example which is a (ii) acid. It is neutralised by alkalies and forms salts called (iii) . Acids react with metals to give (iv) gas.
          (i)                    (ii)                 (iii)                  (iv)
A. Hydrogen          Weak          Sulphites          Oxygen
B. Oxygen            Weak           Sulphates         Hydrogen
C. Hydrogen         Strong         Sulphites          Oxygen
D. Hydrogen         Strong         Sulphates         Hydrogen
Answer : D

Question. Which of the following statements are true?
I. In the luminous zone of candle flame, vaporised wax gets oxidised to carbon dioxide which burns with a blue flame.
II. There is no burning in the dark inner zone of the flame.
III. Non luminous zone is the hottest part of the flame.
IV. Luminous zone of a f lame is mainly due to incomplete burning of carbon.
A. I and III only
B. II and III only
C. II, III and IV only
D. All of these
Answer : C

Question. Rahul, a class 8 student conducted the following experiment and recorded the observations in the given table.

The correct observation and inference drawn are
A. I, balloon has a higher ignition temperature than water hence, it explodes
B. II, water increases the melting point of balloon
C. III, water in the balloon absorbs the heat
D. II, water conducts the heat away from the balloon.
Answer : D

Question. The characteristics of different fibres are listed as
W : I am strong, elastic, light and burn slowly.
I shrink on heating and form hard beads with smell of burning hair.
X : I burn completely leaving no residue.
Y : I can be woven like silk fibres and dyed in a wide variety of colours. I burn quickly with a smell of burning paper.
Z : I do not get wrinkled easily. I burn slowly and produce black smoke.
W, X, Y and Z are respectively
A. Terylene, rayon, cotton and nylon
B. Bakelite, nylon, rayon and cotton
C. Melamine, PVC, nylon and rayon
D. Nylon, cotton, rayon and polyester.
Answer : D

Question. Refer to the given Venn diagram and select the correct option regarding P, Q and R.

A. Plant P possesses special root like structures called haustoria for absorption of nitrogen from atmospheric air.
B. Plant Q catches and digests insects and shows completely heterotrophic mode of nutrition.
C. R could be Nepenthes or Rafflesia.
D. P could be Dionaea whereas Q could be Cuscuta.
Answer : D

Question. Refer to the given figures and select the correct option regarding species P, Q and R.

A. Fruits of species P burst open forcibly after drying and seeds are scattered nearby.
B. Seeds of species R possess wings or hair-like structures.
C. P could be Hiptage whereas Q could be balsam.
D. Seeds of species Q are heavy and bear spines or hooks.
Answer : A

Question. Read the given paragraph with few blanks and select the option that correctly fills up any 3 of these.
(i) is the ability to blend with the surroundings.
It is protective to prey insects like (ii) and also advantageous to predators like (iii) .
(iv) is the resemblance of one species with another.
The species which is imitated is called (v) while the species which imitates is called (vi) .
A. (i) – Mimicry, (iv) – Camouflage, (vi) – Mimic
B. (ii) Leaf insect, (iv) – Mimicry, (v) – Model
C. (i) – Camouflage, (iii) – Praying mantis, (vi) – Model
D. (ii) – Grasshopper, (iii) – Stick insect, (v) – Mimic

Answer : B

Question. The given figure represents the pattern of blood circulation in human body.

Select the correct statement regarding this.
A. Q and R carry deoxygenated blood whereas P and S carry oxygenated blood.
B. X represents right side of heart, i.e., right atrium and ventricle.
C. Q and P carry oxygenated blood whereas R and S carry deoxygenated blood.
D. Y represents left side of heart, i.e., left atrium and ventricle.
Answer : C

Question. The given figure shows positions of few endocrine glands in human body. 
Two patients, Ravi and Sohail recently visited an endocrinologist regarding their health issues.
Doctor examined them and prepared a chart shown here to keep a record of their illness and monitor their health.

Refer to the given figure and chart and select the correct option.
A. Ravi is suffering from goitre which is caused due to hyposecretion of a hormone by gland X.
B. Ravi is suffering from cretinism which is caused due to hypersecretion of a hormone by gland Y.
C. Sohail is suffering from diabetes which is caused by hyposecretion of a hormone by gland W.
D. Sohail is suffering from diabetes which is caused by hypersecretion of a hormone by gland Z.
Answer : A

Question. X and Y are two groups of microorganisms. Group X includes all unicellular forms which lack an organised nucleus. Group Y includes both unicellular and multicellular forms with organised nucleus. Both groups do not possess chlorophyll.
Identify the groups and select the correct statements regarding them.
(i) Several species of groups X and Y help in decomposition of biodegradable wastes, thus help in waste disposal.
(ii) Some species of groups X and Y possess thread like structures called hyphae.
(iii) Species of X cause tuberculosis and anthrax diseases in animals whereas species of Y cause rust and smut diseases in plants.
(iv) Some species of X help in manufacture of ethyl alcohol whereas several species of Y help in biological nitrogen fixation.
(v) Several species of groups X and Y are used in making antibiotics.
A. (i), (ii) and (iii) only
B. (i), (iii) and (v) only
C. (ii) and (iv) only
D. (iv) and (v) only
Answer : B

Question. Study the given flow chart.

Which of the following holds true for P, Q, R, S and T ?
A. P takes part in cell autophagy and autolysis whereas Q takes part in osmoregulation.
B. R takes part in protein synthesis and is also present in bacteria.
C. Inner membrane of T contains stalked particles whereas inner membrane of S is connected to thylakoids at various places.
D. T takes part in preparation of food whereas S takes part in oxidation of food to release energy.
Answer : C

Question. The given diagram shows a respirometer that is used to measure gaseous exchange in pea seeds. The apparatus is maintained at a constant temperature.
Which of the following is incorrect regarding this?

A. The gas pressure in X will fall as O₂ is absorbed during respiration and CO₂ is absorbed by potassium hydroxide solution.
B. The fluid level at Y will fall to compensate the loss of pressure in X.
C. The gas pressure at X will rise as O₂ is given out by seeds and CO₂ is released by potassium hydroxide solution.
D. The fluid level at Z will rise due to loss of pressure at X.
Answer : C

Question. Refer to the given diagram of human male reproductive system and select the incorrect statement regarding parts X, Y and Z.

A. Z deposits sperms into the vagina of female during coitus.
B. Y is similar in function to ovaries of female.
C. X conducts sperms from testis to urethra.
D. Y lies within scrotum in the abdominal cavity.
Answer : D

Question. Identify P, Q and R in the given flow chart and select the correct option regarding them.

A. P – Passenger pigeon, Q – Golden langur, R – Great Indian bustard
B. P – Sloth bear, Q – Chinkara deer, R – Asian elephant
C. P – Olive Ridley turtle, Q – Komodo dragon, R – Blue whale
D. P – Dodo, Q – Red panda, R – Indian rhinoceros
Answer : D

Question. Read the following statements and select the correct option.
A. A daughter receives X-chromosome from her mother only.
B. Human beings possess 22 pairs of autosomes and 1 pair of sex chromosomes.
C. A new human individual develops from a cell called gamete only.
D. Pituitary gland produces thyroxine.
Answer : B

Question. Match column I with column II and select the correct option from the given codes.
     Column I                        Column II
P. Anopheles         (i) A fungus from which antibiotic is obtained
Q. Rhizobium        (ii) A viral disease
R. Penicillium        (iii) A bacterium responsible for curdling of milk
S. Hepatitis B        (iv) Nitrogen fixing bacterium
T. Lactobacillus     (v) Edible fungus
U. Mushroom        (vi) Vector for malarial parasite
A. P-(vi), Q-(iv), R-(i), S-(ii), T-(iii), U-(v)
B. P-(ii), Q-(v), R-(iii), S-(i), T-(vi), U-(iv)
C. P-(iv), Q-(vi), R-(i), S-(v), T-(ii), U-(iii)
D. P-(i), Q-(iii), R-(iv), S-(ii), T-(vi), U-(v)
Answer : A

ACHIEVERS SECTION

DIRECTION (Q. No. a and b) : Refer to the given passage and answer the following questions.
A balloon is moving upwards from ground with a constant speed of 10 m s–1 at a distance 5 m infront of a plane mirror of length 2 m as shown in figure.
A source S is placed symmetrically before plane mirror.
The plane mirror is placed at a height H = 15 m above the surface of ground.

Question a. The maximum time interval during which a man inside the balloon can see the image of the source in the mirror is
A. 2.2 s
B. 1.7 s
C. 4.6 s
D. 0.5 s
Answer : A

Question b. When the balloon is at a height of 17 m from the ground, the man drops a stone from it then the maximum height attained by the stone will be (g = 10 m s^–2)
A. 17 m
B. 20 m
C. 22 m
D. 27 m
Answer : C

Question. The given graph shows the changes in various factors (P, Q and R) present in a water body after the sewage discharge at point X.

Refer to the given graph and select the correct option regarding P, Q and R.
A. P could be bacteria which increase tremendously in number to decompose nitrogen rich sewage.
B. Q corresponds to biological oxygen demand which decreases due to accumulation of sewage on water surface.
C. R could be aquatic animals like fish which die on account of non-availability of dissolved oxygen.
D. Both A and C
Answer : D

Question. Ms. Deepika, a science teacher demonstrated an activity in the science lab and the experiment was set up as shown in the figure.

The metal ‘X’ reacts with steam to form a gas ‘Y’ which is collected in the syringe.
Which of the following best describes the metal ‘X’ and gas ‘Y’?
A. Metal ‘X’ is silver and gas ‘Y’ is hydrogen which burns with a pop sound.
B. Metal ‘X’ is sodium and gas ‘Y’ is carbon dioxide which gives white precipitate with lime water.
C. Metal ‘X’ is iron and gas ‘Y’ is hydrogen which burns with a pop sound.
D. Metal ‘X’ is magnesium and gas ‘Y’ is carbon dioxide which gives white precipitate with lime water.
Answer : C

Question. Read the given paragraph where few words have been italicised.
Preparation of soil in a field, before sowing of seeds involves two steps : broadcasting and levelling. Soil in the crop field is enriched with nutrients by adding manures and fertilisers to it. Crop fields need to be irrigated from time to time. In sprinkler system of irrigation water is allowed to fall drop by drop from a pipe just near the plant roots whereas in drip irrigation water escapes from a revolving nozzle. Weeding in crop fields can be done using thresher. After the crop is harvested, the grain is separated from cut crop using a machine called harvester.
Select the correct option regarding these.
A. Broadcasting should be replaced by winnowing.
B. Positions of sprinkler system and drip irrigation should be interchanged.
C. Thresher should not be replaced as it is correctly mentioned.
D. Harvester should be replaced by seed drill
Answer : B