CBSE Class 8 Science NSO Olympiad MCQs with Answers Set A

LOGICAL REASONING

Question. Select the option which will replace the question mark in the given number series.
10, 100, 200, 310, ?
A. 400
B. 410
C. 420
D. 430
Answer : D

Question. Mr. ‘X’ shows three photographs to Mr. 'Y'. Pointing towards photograph 1, he says, “The person in photograph 1 is my uncle, who says ‘uncle’ to the person in photograph 2, and the person in photograph 3 is called ‘uncle’ by the person in photograph 2.” How is Mr. ‘X’ related to the person in photograph 2?
A. Grandson
B. Granddaughter
C. Great grandson
D. None of these
Answer : A

Question. At a dinner party, both fish and meat were served.
Some took only fish while some took only meat.
There were some vegetarians also who did not accept either of the two, while the rest accepted both fish and meat. Which of the following Venn diagrams correctly represents this situation?

Answer : A

Question. Six people P, Q, R, S, T and U are sitting on the ground in a hexagonal shape. All the sides of the hexagon, so formed, are of same length. P is not adjacent to Q or R; S is not adjacent to R or T; Q and R are adjacent; U is in the middle of S and R.
Who is at the same distance from S as T is from S?
A. Q
B. R
C. U
D. Can't be determined
Answer : B

Question. Select the pair of figures which satisfies the same conditions of placement of dots.

A. I, II
B. II, III
C. III, IV
D. I, IV
Answer : B

Question. If the alphabets are written in the reverse order after interchanging alphabets from ‘D to L’ with those from ‘R to Z’ respectively, which letter would be midway between W and E in the new order?
A. Z
B. N
C. D
D. None of these
Answer : B

Question. If Fig. (X) is rotated one step in a particular direction, then identify its rotated form, from the given option figures.

Answer : D

Question. Select a figure from the given options which will complete the given figure matrix.

Answer : B

Question. Three of the following four numbers are alike in a certain way and so form a group. Which of the following does not belong to that group?
A. 143
B. 399
C. 759
D. 257
Answer : D

Question. There are seven figures, the first and last of which are unmarked and remaining are marked as P, Q, R, S and T. However, the series will be established only if the positions of two of the marked figures are interchanged. Find the figures.

A. PQ
B. QR
C. QT
D. ST
Answer : B

Question. A pile of cubes of equal size is arranged in the form of a block as shown in the figure. If the block is dipped into a bucket filled with red paint, so that only the surfaces of the block get coloured, then how many cubes are coloured on three faces only?

A. 14
B. 15
C. 16
D. 12
Answer : B

Question. Two series in two rows are given below. In the first row, a full series is given which follows a specific pattern. The second row has a series, similar to the first series but only first element of this series is given, followed by (a), (b), (c), (d) and (e), representing the subsequent elements. Complete the series and answer the question that follows :
7 24 10 33 14.5 46.5
11 (a) (b) (c) (d) (e)
What will come in place of (b)?
A. 21
B. 23.5
C. 19.5
D. 16
Answer : D

Question. There are five different successive figures showing movement of the hands in a clock. Identify the pattern and find the next figure.

Answer : D

Question. In a code language, each of the vowels, i.e., A, E, I, O and U, is substituted by the letter preceding it, while a consonant is substituted by the nearest vowel. How can the word EVIDENCE be written in that code?
A. DUHJEDOED
B. DUHEDUAD
C. DUJEDOAD
D. DUHEDOAD OR DUHEDOED
Answer : D

Question. At my farmhouse I am facing East, then I turn left and walk 10 metres. I again turn right and walk 5 metres. Again I go 5 metres towards the South, and from there walk 5 metres towards the West. In which direction am I from my farmhouse ?
A. East
B. West
C. North
D. South
Answer : C

SCIENCE

Question. When a constant force acts on a mass, and the mass starts moving from rest, then the
(i) acceleration is constant
(ii) velocity increases at a constant rate
(iii) distance travelled is directly proportional to the time.
Which of the above statements is/are correct?
A. (i) only
B. (i) and (ii) only
C. (i) and (iii) only
D. (ii) and (iii) only
Answer : B

Question. Which planet is called the morning star as well as the evening star, depending on its position with respect to the sun?
A. Mercury
B. Venus
C. Mars
D. Saturn
Answer : B

Question. The displacement-time graph of a body in motion is shown here. The corresponding velocity-time graph will be

Answer : A

Question. A man standing in front of a large wall, claps two objects against each other at an interval of 1.2 s regularly. The echo of the first clap coincides with the fifth clap. If the speed of sound in air is 340 m s–1, the distance between the man and the wall is ____.
A. 408 m
B. 1632 m
C. 816 m
D. 204 m
Answer : C

Question. The image formed by the side-view mirror of an automobile is
(i) of the same size as that of object
(ii) virtual and diminished
(iii) erect and real
(iv) erect and magnified.
Which of the following statements is/are correct?
A. (i) only
B. (ii) only
C. (i) and (iii) only
D. (iii) and (iv) only
Answer : B

Question. The diagram shows a man standing at a position M in front of a plane mirror, a distance of x m from the mirror.

When the man moves 3 m away from the mirror, the new distance between the man and his image becomes 12 m. What is the value of x? 
A. 1 m
B. 2 m
C. 3 m
D. 4 m
Answer : C

Question. A substance in gaseous form is being cooled to solid state. Its temperature will remain constant when the substance is
(i) in condensing phase
(ii) in freezing phase
(iii) at thermal equilibrium with the environment.
A. (i) only
B. (iii) only
C. (i) and (ii) only
D. (i), (ii) and (iii)
Answer : D

Question. During a track and field meet, the time difference between seeing the smoke from a starter's gun and hearing the bang would be less ______.
A. On a warmer day
B. On a cooler day
C. If a more powerful shell were used
D. If a less powerful shell were used
Answer : A

Question. Read the given statements and mark the correct option.
Statement-1 : A convex mirror always forms a real image.
Statement -2 : A diverging beam incident on a convex mirror is reflected as a diverging beam.
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 false but statement 2 is true. 
D. Both statements 1 and 2 are false.
Answer : C

Question. A cube of side 0.2 m rests on the floor, as shown. Given that the cube has a mass of 50 kg, the pressure exerted by the cube on the floor is ________.

(Take g = 10 N kg^–1)
A. 25 N m^–2
B. 250 N m^–2
C. 1250 N m^–2
D. 12500 N m^–2
Answer : D

Question. In an electrical circuit containing a battery, the positive charge inside the battery ________.
A. always goes from positive terminal to the negative terminal
B. may go from positive terminal to negative terminal
C. always goes from the negative terminal to positive terminal
D. does not move
Answer : A

Question. A plank is supported on the steps of a staircase as shown in the figure. How many forces are acting on the plank?

A. 4 Plank
B. 5
C. 6
D. 7
Answer : D

Question. How do cyclones decrease the fertility of soil in the coastal areas?
A. By flooding the land with saline water.
B. By dissolving soil and rocks.
C. By increasing the water table of the place.
D. By decreasing the water table of the place.
Answer : A

Question. Read the given statements and select the correct option.
Statement-1 : Petroleum is called ‘black gold’.
Statement-2 : Petroleum is a dark oily liquid.
A. Both statements 1 and 2 are true but 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. Read the table carefully

Identify the products formed and their nature.
A. (1) Cu(OH)₂, CuCO₃; basic
(2) H₂; neutral
(3) Fe₂O₃; basic
(4) SO₂; acidic
B. (1) CuO; basic
(2) O₂; neutral
(3) Fe₃O₄; basic
(4) H₂S; acidic
C. (1) Cu(OH)₂, CuCO₃; basic
(2) H₂; neutral
(3) Fe₂O₃; acidic
(4) SO₂; basic
D. (1) Cu; basic
(2) H₂O; neutral
(3) FeO, basic
(4) SO₃; basic
Answer : A

Question. Which of the following examples are periodic changes?
I. Occurrence of eclipse.
II. The flowering of jasmine bush.
III. Occurrence of new moon.
IV. Opening and closing of stomata.
V. Appearance of rainbow.
VI. Rotation of earth.
VII. Blinking of eyes.
VIII. Twinkling of stars.
A. I, V, VII and VIII
B. I, II, III and IV
C. II, III, IV and VI
D. All are non-periodic changes.
Answer : C

Question. Neha, a class VIII student arranged the following experimental set-up and observed the changes carefully.

On the basis of her observations identify the correct order of reactivity.
A. Zn > Cu > Fe
B. Zn > Fe > Cu
C. Fe > Zn > Cu
D. Cu > Fe > Zn
Answer : B

Question. Identify V, W, X, Y and Z in the given Venn diagram.

Answer : B

Question. Different mixtures are taken in four different test tubes and each of them is tested with indicators as shown below :

Select the incorrect observation.
A. No change in colour in test tubes 1 and 3.
B. Turmeric solution turns red in test tube 2.
C. China rose turns magenta in test tube 4.
D. None of the above
Answer : A

Question. Match the articles given in Column-I with the fibres/plastics from which they are made in Column-II.
           Column-I                    Column-II
(a) Toothbrush bristles         (i) Melamine
(b) Carpet                           (ii) PVC
(c) Bottle                            (iii) Nylon
(d) Toy                               (iv) Rayon
(e) Fire resistant fabric       (v) PET
A. (a)-(i), (b)-(iv), (c)-(ii), (d)-(v), (e)-(iii)
B. (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i), (e)-(v)
C. (a)-(iii), (b)-(iv), (c)-(v), (d)-(ii), (e)-(i)
D. (a)-(iii), (b)-(v), (c)-(iv), (d)-(i), (e)-(ii
Answer : C

Question. The manufacture of bread, beer and wine involves alcoholic fermentation of glucose to ethanol by yeast.
Which of the following five statements concerning this process are correct?
I. Yeast carries out fermentation because yeast cells lack mitochondria.
II. For every molecule of ethanol produced, one molecule of CO2 evolves.
III. For every one molecule of glucose fermented, net two molecules of ATP are generated.
IV. More than 80% of the chemical energy of the glucose is released as heat.
V. Glycolysis is an integral part of this fermentation.
A. II, III and IV
B. I, II, III and V
C. II, III and V
D. I, IV and V
Answer : C

Question. Thyroxine controls _______ in frogs and the development of _______ and ______ during embryonic development of other vertebrates. Thyroxine production requires the presence of ______ in diet.
Select the correct sequence of words to complete the above passage.
A. Development, Circulatory system, Muscles, Iodine
B. Metamorphosis, Circulatory system, Muscles, Calcium
C. Development, Bones, Nervous system, Iron
D. Metamorphosis, Bones, Nervous system, Iodine
Answer : D

Question. The given pie charts show the composition of three types of soil samples X, Y and Z. Which of the following is correct regarding these soil samples?

A. X is unable to hold water or nutrients.
B. Y is used for pot making.
C. Z provides good aeration to plant roots.
D. X is best suited for cultivation.
Answer : D

Question. Read the given statements and select the correct option.
Statement-1 : Chloroplast and mitochondria are semi-autonomous organelles.
Statement-2 : Chloroplast and mitochondria have their own DNA and protein synthesizing machinery.
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 : A

Question. The names of some plants are given below in the list :
I. Lady’s finger VI. Grass
II. Drumstick VII. Xanthium
III. Balsam VIII. Madar
IV. Urena IX. Sunflower
V. Maple X. Coconut
Match these plants with the mode of dispersal of their fruits/seeds and select the correct option.

Answer : B

Question.

Some steps involved in the treatment of water in a wastewater treatment plant are labelled as P, Q, R and S in the above diagram. The table given below shows (✔) for those steps in which the particular process is occurring while (X) for those in which it is not occurring. Which among these is/are incorrect?

A. I and II
B. III and IV
C. II only
D. None of these
Answer : D

Question. According to the extent of threat to a species and its population in its natural habitat, four categories have been identified which are given below :
I. Extinct in wild
II. Critically endangered species
III. Vulnerable species
IV. Endangered species
Select the correct order of these species according to their conservation priority?
A. II > IV > I > III
B. I > II > IV > III
C. III > I > II > IV
D. I > IV > III > II
Answer : B

Question. Refer to the given figures of bacteria (X, Y and Z) and read the statements I, II & III regarding these.
Based on the given information, identify the bacterium and select the correct option.

I. Bacteria X causes cholera.
II. Bacteria Y causes a disease which disrupts proper exchange of gases.
III. Bacteria Z converts lactose sugar of milk to lactic acid.
A. X is Vibro cholerae.
B. Z is Lactobacillus.
C. Y is Salmonella typhi.
D. Both A and B
Answer : D

Question. Following investigation was carried out using flower buds growing on three plants of the same species.
Plant X → The anthers were carefully removed, and the buds left open to the air.
Plant Y → The anthers were left untouched, and a paper bag was tied tightly around each bud.
Plant Z → The anthers were carefully removed, and a paper bag was tied tightly around each bud.
Although all flowers later bloomed normally, only those on plant X, produced seeds. This result showed that in this species _____ pollination can take place.
A. Only insect
B. Only cross
C. Only wind
D. Either of A, B or C
Answer : D

Question. Match Column I with Column II and select the correct option from the codes given below.
      Column I                Column II
(a) SPM              (i) Poisoning of bald eagles
(b) Typhoid         (ii) Green house gas
(c) CO                (iii) Vehicle exhaust
(d) CO₂              (iv) Incomplete combustion
(e) DDT              (v) Pathogens in polluted water
     a     b      c      d    e
A. iii     v      ii      iv     i
B. i       iii     iv      ii    v
C. iii     iv     v      ii     i
D. iii     v      iv     ii     i
Answer : D

ACHIEVERS SECTION

Question.

The given graph shows two crop fields (X and Y) that have been treated by different types of materials for nutrient replenishment, keeping other environmental factors same. Given are some assumptions regarding the crop fields and the materials used. Select the most correct one(s).
I. Addition of chemical fertilizers in Y has resulted in sudden increase in yield due to increased release of N, P, K nutrients, but it gradually declined as continuous use of chemicals killed useful microbes that replenish the soil fertility.
II. The difference in the two graphs indicates that the crop fields X and Y are treated with fertilizer and manure respectively, as fertilizer is beneficial for long time and gives durable yield whereas manure gives immediate yield but later causes problems.
III. The highest peak in crop field X is slightly delayed because manure enriches soil fertility gradually.
A. I and II
B. II only
C. III only
D. I and III
Answer : D

Question. A large number of functions are performed by different hormones secreted by endocrine glands. Match the given functions (a, b,
c, d and e) to the labelled glands in the figure and select the correct option.
a. Maintains a steady level of glucose in the blood.
b. Helps in the growth of human body and also sends signals to other organs to secrete hormones.
c. Controls secondary sexual characters and maintains pregnancy.
d. Controls rate at which food is oxidised by the cells to produce energy.
e. Increases blood pressure and heart rate, when the body experiences stress.

Answer : D

Direction (Q.No. a and b): Refer to the given passage and answer the following questions:
Ram jogs from one end X to the other end Y of a straight 300 m road in 2 minutes 30 seconds, and then turns around and jogs 100 m back to point Z in another 1 minute.

Question a. What is Ram’s average speed and average velocity while jogging from X to Y respectively?
A. 1.0 m s^–1 , 1.0 m s^–1
B. 3.0 m s^–1, 2.0 m s^–1
C. 2.0 m s^–1, 2.0 m s^–1
D. 4.0 m s^–1, 1.0 m s^–1
Answer : C

Question b. What is Ram’s average speed and average velocity while jogging from X to Z respectively ?
A. 2.0 m s^–1, 1.9 m s^–1
B. 5.1 m s^–1, 9.1 m s^–1
C. 1.0 m s^–1, 1.0 m s^–1
D. 1.9 m s^–1, 0.9 m s^–1
Answer : D

Question. Sakshi performed two experiments as shown in figure 1 and 2, and recorded her observations in the table.

Find out the correct observation and the reason behind it from the options given below.
A. I, paper has a higher ignition temperature than water.
B. II, fireproof paper pan is used in figure 2.
C. III, paper is non-inflammable.
D. II, heat supplied to the paper pan is transferred to water by conduction, so ignition temperature ofpaper is not reached in figure 2.
Answer : D