CBSE Class 8 Science NSO Olympiad MCQs with Answers Set K

MENTAL ABILITY

Question. Factorise : 15(x – 2y)2 – 8(x – 2y) – 16
A. (5x + 10y – 9)(3x + 2y – 4)
B. (9x – 4y)(x – 2y)
C. (5x – 10y + 4)(3x – 6y – 4)
D. (9x – 4y + 3)(3x – 2y + 4)
Answer : C

Question. A person has enough money to buy 25 cycles worth ₹ 500 each. How many cycles will the person be able to buy, if each cycle now costs ₹ 125 more?
A. 40 cycles
B. 70 cycles
C. 20 cycles
D. 65 cycles
Answer : C

Question. It is possible to make a meaningful word with the second, the third, the ninth, the tenth, the thirteenth, the fourteenth and the eighteenth letters of the word COUNTERINTELLIGENCE, using each letter only once, except the second letter, which should be used twice, which of the following will be the third letter of that word? If no such word can be formed give ‘X’ as the answer, and if only two such words can be made give answer ‘Y’. And if more than two such words can be formed give answer ‘Z’.
A. C
B. X
C. Y
D. Z
Answer : A

Question. Which of the following numbers will be obtained if the second digit of the lowest number is added to the third digit of the highest number after adding 4 to each number?
129 642 921 476 308
A. 5
B. 6
C. 7
D. 8
Answer : D

Question. Simplify : 9^5/2 - 3X7⁰ - (1/81)^1/2 / (27)^2/3 - (8/27)^2/3
A. 0
B. 16
C. 27
D. 77
Answer : C

Question. Read the following information and answer the question given below it:
1. Seven students P, Q, R, S, T, U and V take a series of tests.
2. No two students get the same marks.
3. V always scores more than P.
4. P always scores more than Q.
5. Each time either R scores the highest and T gets the least, or alternatively S scores the highest and U or Q scores the least.
If S is ranked sixth and Q is ranked fifth, which of the following can be true?
A. V is ranked first or fourth.
B. R is ranked second or third.
C. P is ranked second or fifth.
D. U is ranked third or fourth.
Answer : D

Question. If the first element from the left end interchanges place with the tenth element from the left end, similarly second with ninth, third with eighth, fourth with seventh, and so on, then which of the following will be seventh to the left of eighth element from the right end?
A B 7 C D 9 Z Y ★ © P 2 M C K S 3 5 N T @
A. 9
B. 7
C. D
D. C
Answer : D

Question. Divide : 30x3y2 – 20xy3 + 12xy – 13y by – 5xy
A. −6x²y+4y² − (12/5 + 13/5x)
B. −6x²y-4y² + (12/5 + 13/5x)
C. −6x²y+4y² − 5 + 13
D. −6x²y-4y² + 11/6 - 12
Answer : A

Question. A cylindrical container of radius 28 cm contains sufficient water to submerge a rectangular solid of dimensions 32 cm × 22 cm × 14 cm. Find the rise in the level of water, when the solid is completely submerged.
A. 6 cm
B. 4 cm
C. 7 cm
D. 9 cm
Answer : B

Question. Akash purchased two articles for ₹ 750 each. He sold these articles, gaining 6% on one and losing 4% on the other. Find his gain or loss per cent in the whole transaction.
A. 2% loss
B. 3% gain
C. 1% gain
D. 1% loss
Answer : C

Question. Ashok took a loan of ₹ 2400 from a finance company at 15% p.a. simple interest for 2 years. He lent it to Rajesh at the same rate of interest, compounded annually. Find the gain of Ashok after 2 years.
A. ₹ 54
B. ₹ 20
C. ₹ 45
D. ₹ 64
Answer : A

Question. The given pie chart shows what Mr. Varun does with his monthly income of ₹ 3000.

If he spends the same amount every month on food, how long does he take to spend ₹ 14400 on food?
A. 10 months
B. 540 months
C. 1 year
D. 1(1/2)years
Answer : C

Question. Select the Venn diagram which best illustrates the relationship between : "Nurse, Doctor, Women".

Answer : D

Question. In the given figure (not drawn to scale), ACE and BCD are straight lines. Find the value of ∠w + ∠x + ∠y + ∠z.

A. 150°
B. 175°
C. 200°
D. 210°
Answer : D

Question. The sum of numerator and denominator of a fraction is 10. If the numerator is increased by 1 and denominator is reduced by 1, then value of the fraction would be 2/3. Find the fraction.
A. 5/7
B. 3/7
C. 4/7
D. 2/7
Answer : B

SCIENCE

Question. A hockey player is moving northward and suddenly turns westward with the same speed to avoid an opponent.
The force that acts on the player is ________.
A. Frictional force along westward
B. M uscle force along southward
C. Frictional force along south-west
D. M uscle force along south-west.
Answer : C

Question. Water waves produced by a motor boat sailing in water are ________.
A. Neither longitudinal nor transverse
B. Both longitudinal and transverse
C. Only longitudinal
D. Only transverse.
Answer : B

Question. A Centigrade and Fahrenheit thermometers are dipped in boiling water. The water temperature is lowered until the Fahrenheit thermometer registers 140. The fall in temperature as registered by centigrade thermometer is ________.
A. 30°
B. 40°
C. 60°
D. 80°
Answer : B

Question. Earthquakes can occur because of ________.
A. M ovement of tectonic plates
B. Volcanic eruption
C. M ine blasts
D. All of these.
Answer : D

Question. The direction of a ray of light incident on a concave mirror is shown by PQ while directions in which the ray would travel after reflection is shown by four rays marked 1, 2, 3 and 4.
Which of the four rays correctly shows the direction of reflected ray ?

A. 4
B. 3
C. 2
D. 1
Answer : C

Question. A motor cyclist rides around the well with a round vertical wall and does not fall down while riding because ________.
A. The force of gravity disappears
B. He loses weight some how
C. He is in this path due to the force exerted by surrounding air
D. The frictional force of the wall balances his weight.
Answer : D

Question. An air conditioner is rated 240 V, 1.5 kW. The air conditioner is switched on for 8 hours each day. How much electrical energy is consumed in 30 days?
A. 360 kW h
B. 8.64 kW h
C. 120 kW h
D. 240 kW h
Answer : A

Question. Read the given statements and select the correct option.
Statement-1 : Echo is produced when sound is incident on hard and polished surface.
Statement-2 : Sound energy can be totally reflected by objects with soft and loose texture.
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. A stone which has a mass of 12 g and a density of 3 g cm–3, is lowered into 20 cm3 of water in a measuring cylinder. What will be the new reading on the measuring cylinder?
A. 20 cm³
B. 24 cm³
C. 40 cm³
D. 16 cm³
Answer : B

Question. A planet is revolving around the sun in an elliptical orbit. Which of the following remains constant ?
A. Linear momentum
B. Angular momentum
C. Kinetic energy
D. Potential energy
Answer : B

Question. Read the given statements and select the correct option.
Statement-1 : A horse has to pull a cart harder during the first few steps of his motion.
Statement-2 : The first steps are always difficult.
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. The nearest and farthest planets from the sun are ________ respectively.
A. Mars and Venus
B. Mercury and Pluto
C. Venus and Pluto
D. Earth and Neptune.
Answer : B

Question. An under-water swimmer cannot see very clearly even in absolutely clear water because of
A. Absorption of light in water
B. Scattering of light in water
C. Reduction of speed of light in water
D. Change in the focal length of eye lens.
Answer : D

Question. Study the given Venn diagram carefully.
Identify the points which represent polycot and rayon respectively.

A. 2, 4
B. 4, 3
C. 1, 2
D. 3, 1
Answer : D

Question. Choose the correct statement among the following.
A. The substances which vapourise during burning, do not give flames.
B. The subs t anc e s whi ch have ve ry high ignition temperature are called inflammable substances.
C. When the match is struck against the rubbing surface, some red phosphorus gets converted into white phosphorus.
D. The job of a fire extinguisher is to cut off the supply of carbon dioxide, and hence the fire is controlled.
Answer : C

Question. Using the given hints, identify the option with correct coal product and its use.
(1) Almost pure form of carbon.
(2) Mixture of about 200 substances.
A. (1) - Coke, manufacture of steel
B. (1) - Coal tar, manufacture of paints
C. (2) - Coke, manufacture of plastics
D. (2) - Coal tar, extraction of metals
Answer : A

Question. An element X is soft and dull in appearance. It reacts with oxygen to form Y, which when dissolved in water, forms Z. Z turns China rose indicator to magenta colour. Identify Z.
A. Sulphuric acid
B. Sulphurous acid
C. Nitrous acid
D. Nitric acid
Answer : B

Question. Fill in the blanks in the given paragraph by choosing the correct option.
Over million of years, absence of air, _____p______ temperature and ____q______ pressure transformed the dead organisms into ____r_____ and s.
One of the various constituents of s, _____x______ is used in paints and road surfacing

Answer : B

Question. Observe the given diagrams carefully.

A circular blackish ring is formed on the glass slide due to _______.
A. Deposition of unburnt wax particles present in the non-luminous zone of the flame
B. Deposition of unburnt carbon particles present in the luminous zone of the flame
C. P artial combustion of wax in yellow middle zone of the flame
D. Incomplete combustion of carbon particles in outer blue zone of the flame.
Answer : B

Question. Match Column I with Column II and choose the correct option using the codes given below.
     Column I                   Column II
p. Teflon                (i) Making electrical switches
q. P VC                 (ii) Flame resistant
r. M elamine         (iii) Non- stick coating of cookwares
s. Bakelite            (iv) Thermoplastic
A. p - (ii), q - (i), r - (iv), s - (iii)
B. p - (i), q - (ii), r - (iii), s - (iv)
C. p - (iv), q - (iii), r - (i), s - (ii)
D. p - (iii), q - (iv), r - (ii), s - (i)
Answer : D

Question. Why animals like frog and fish produce hundreds of eggs while hens and humans produce one egg at a time?
A. In frogs and fish, internal fertilization occurs.
B. Eggs of hens and humans are exposed to external environment.
C. Eggs of frogs and fish are produced inside the mother’s body and hence they are protected.
D. Eggs of frogs and fish are preyed by predators and are exposed to environment.
Answer : D

Question. A farmer has a cropping field which is specifically deficient in nitrogen. He divided his field into three parts i.e., d, e and f. He wants to grow cereal crops for three successive seasons. He supplied field ‘d’ with ammonium nitrate and ammonium sulphate and field ‘e’ with manure. He grew crop of pulses between cereal crops in field ‘f ’. Which of the following best represents the effect of these different treatments on the crop yield after three crop seasons?

Answer : C

Question. A farmer’s crop is repeatedly getting infected from a fungal disease. The soil in which crop is sown is clayey. Which of these irrigation methods would lessen the chance of infection?
A. Furrow irrigation
B. Drip irrigation
C. Basin irrigation
D. Sprinkler irrigation
Answer : B

Question. Match the columns and select the correct option.
            Column I                             Column II
(a) Pencillium notatum            (i) Production of yoghurt
(b) Chlorella                            (ii) Nitrogen fixation
(c) Rhizobium                         (iii) Sewage disposal
(d) E.coli                                 (iv) Antibiotics
                                               (v) Production of vitamins in the large intestine
A. a-(iii), b-(v), c-(ii), d-(i)
B. a-(iv), b-(iii), c-(ii), d-(v)
C. a-(iv), b-(ii), c-(iii), d-(v)
D. a-(v), b-(iv), c(ii), d-(i)
Answer : B

Question. The given figure shows a typical animal cell with its parts being labelled as ‘a – j’. Identify the labelled parts and select the incorrect option regarding it.

A. The organelles e, h, g and i are membrane-bound organelles which function in close coordination with one another.
B. ‘forganelle is responsible for the synthesis of fats inside the cells and it stores Ca2+ for release during muscle contraction.
C. a and b have selective permeability i.e., they allow only selected substances to pass inwardly.
D. ‘j’ is the site for protein synthesis. It allows hereditary message from ‘d’ to get translated into proteins.
Answer : B

Question. Read the given statements with one or two blanks and select the option which correctly fill the blanks of any two statements.
(a) _________ is being maintained by _________, which is now known as World Conservation Union.
(b) _______ is specified land area in which multiple use of land is permitted for preserving biodiversity.
(c) __________ are species which are likely to move to ___________ category in near future, if causative factors continue to operate.
(d) ________ are those specific regions of megabiodiversity nations which have large numbers of ___________ species.
A. a - Red Data Book, IUCN
c - Vulnerable, endangered
B. c - Endangered, rare
d - Hot spots, extinct
C. b - Biosphere reserve
d - Hot spots, exotic
D. a - Red Data Book, WWF
b - Wild life sanctuary
Answer : A

Question. Which of the following is not true?
A. Rotation of crops improves the fertility of soil.
B. Rotation of crops saves a lot of nitrogenous fertilizers.
C. Rotation of crops helps in the weed control and pest control.
D. Rotation of crops helps in mixing of nutrients uniformly.
Answer : D

Question. What observation can be made by viewing the slides under the microscope on binary fission in Amoeba and budding in yeast?
A. The daughter cells of Amoeba and the bud of yeast are smaller than their respective parent cells.
B. The daughter cells of Amoeba and the bud of yeast are of the same size as their respective parent cells.
C. The daughter cells of Amoeba are bigger than the parent cells but bud of yeast is smaller than the parents.
D. The daughter cells of Amoeba are smaller than the parents but bud of yeast is larger than the parents.
Answer : A

Question. Identify the given microorganism and select the incorrect statement regarding this.

A. It is a saprophyte commonly called as black bread mould.
B. It reproduces by means of spores.
C. It results in the spoilage of food materials.
D. It is a parasitic fungus that causes various diseases in plants, animals and humans.
Answer : D

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 number of diseases, is called as 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

ACHIEVERS SECTION

Direction (Q. a & b) : The sliding frictional force between a 4 kg box and the floor is 15 N. It is pushed across the floor with a constant force such that it accelerates at 0.8 ms^–2.

46. What is the force applied to the box ?
A. 9.1 N
B. 18.2 N
C. 3.6 N
D. 6.2 N
Answer : B

Question a. If this same force calculated is applied to the box which is now placed on a frictionless floor what is the new acceleration produced?
A. 8.2 ms^–2
B. 16.2 ms^–2
C. 4.6 ms^–2
D. 2.3 ms^–2
Answer : C

Question b. A student performed various experiments to investigate about the reactivities of four unknown elements, P, Q, R, X and Y.

Metals P and R can react with dilute acids to produce hydrogen gas while X cannot.
Identify the correct order of reactivity.
A. Q > Y > P > R > Hydrogen > X
B. Q > X > R > P > Y
C. X > P > Q > Y > R > Hydrogen
D. P > Y > R > Q > Hydrogen > X
Answer : A

Question. The given diagram shows changes in uterine lining during a menstrual cycle (divided in five phases, a to f).

(i) When release of the egg from the ovary is expected to happen?
(ii) When menstruation is expected to occur?
(iii) If the egg gets fertilized, when implantation of embryo is expected to occur?
A. i-d,             ii-a to b,        iii- e to f
B. i-c to d,       ii-e to f,        iii- a to b
C. i-c,             ii-a to b,        iii- d to e
D. i-d to c,      ii-c,               iii- e to f
Answer : C

Question. 

The given diagram represents the plot of a river stream across a town. Water samples are collected from the river from 5 different places P, Q, R, S and T. The BOD of the collected water samples is shown in the following bar diagram

Note : Biological oxygen demand or BOD is a measure of oxygen required by aerobic decomposers for the biochemical degradation of the organic materials.
(a) On which of the places (P to T) the highest amount of organic material is released into the river water?
(b) Where does a water treatment plant most likely built?
A. a - R, b - Between P and Q
B. a - S, b - Between Q and T
C. a - Q, b - Between R and S
D. a - S, b - Between P and R
Answer : B