Science Olympiad Previous Year Paper - 2 | Science Olympiad Class 8 PDF Download
Note: The questions provided in this document are similar to the questions that were asked in the actual Olympiad exam. So, we recommend you study these for your Olympiad preparation.
Logical Reasoning Section
Q1: If 'a' represents '÷', 'b' represents '+', '%' represents '–' and '©' represents '×', what is the result of 28 b 144 a 12 % 6 © 5?(a) 10
(b) 38
(c) 70
(d) 22
View AnswerAns: (a)
- First, replace the symbols with their meanings: 28 + 144 ÷ 12 – 6 × 5.
- Next, perform the operations in the correct order: division and multiplication first, then addition and subtraction.
- Calculate 144 ÷ 12 = 12, and 6 × 5 = 30.
- Now, substitute back: 28 + 12 – 30 = 10.
- Thus, the final answer is 10.
Q2: Find the missing term in the following series:
SCD, TEF, UGH, ____, WKL
(a) CMN
(b) UJI
(c) VIJ
(d) IJT
View AnswerAns: (c)
There are two alphabetical series here. The first series is with the first letters only: S, T, U, V, W. The second series involves the remaining letters: CD, EF, GH, IJ, KL So, VIJ is missing term.
Q3: How many pairs of letters can be found in the word SURPRISE that have the same number of letters between them as their positions in the English alphabet?
(a) One
(b) Two
(c) Three
(d) More than three
View AnswerAns: (c)
- To solve this, we need to look for pairs of letters in the word SURPRISE.
- We check the positions of each letter in the English alphabet and see if the number of letters between them in the word matches that number.
- After analyzing, we find that there are three pairs that meet this criterion.
- Thus, the correct answer is three pairs of letters.
Q4: A and B are siblings. E is the wife of F. D is the son of E. If B is the daughter of F, then how is B related to D?
(a) Brother
(b) Sister
(c) Daughter-in-law
(d) Cousin
View AnswerAns: (b)
A and B are siblings.
E is the wife of F.
D is the son of E.
If B is the daughter of F, it means B is the daughter of E also.
Q5: Complete the following series.
1, 16, 81, 256, ?
(a) 375
(b) 425
(c) 575
(d) 625
View AnswerAns: (d)
The series is as follows:
14 = 1
24 = 16
34 = 81
44 = 256
54 = 625
Q6: In a certain code, "BRAKE" is written as "ASZLD". How will "STONE" be written in that code?
(a) UROND
(a) RUOND
(a) RUNOD
(a) URNOD
View AnswerAns: (c)
The code is as follows:
B – 1 = A
R + 1 = S
A – 1 = Z
K + 1 = L
E – 1 = D
So, in the same way, STONE will be written as:
S – 1 = R
T + 1 = U
O – 1 = N
N + 1 = O
E – 1 = D
Q7: Examine the provided information carefully and respond to the following question: 'A + B' indicates 'A is the son of B'. 'A ÷ B' signifies 'A is the brother of B'. 'A × B' denotes 'A is the father of B'. 'A – B' implies 'A is the sister of B'. Which of the following statements is incorrect regarding P × S + T – V?
(a) P is the brother-in-law of V
(b) T is the father of P
(c) S is the son of V’s sister
(d) S is the nephew of V
View AnswerAns: (b)
- From the symbols, we can deduce relationships: P × S means P is the father of S.
- S + T means S is the son of T, indicating T is the son of P.
- P – V means P is the sister of V, making P a female.
- Thus, T cannot be the father of P, making option (b) incorrect.
Q8: Find the missing term in the following analogy.
MNO : PRT : : STU : ?
(a) UWY
(b) VXZ
(c) WYA
(d) TVX
View AnswerAns: (b)
The relation is as follows:-
M + 3 = P
N + 4 = R
O + 5 = T
In the same way,
S + 3 = V
T + 4 = X
U + 5 = Z
Q9: Find the odd one out.
441, 529, 729, 841, 969
(a) 529
(c) 729
(c) 841
(d) 969
View AnswerAns: (d)
Except 969, all the other numbers are perfect squares.
212 = 441
232 = 529
272 = 729
292 = 841
Q10: If green is blue, black is red, yellow is white and purple is orange, then what are the colours of grass and mango?
(a) Green and Yellow
(b) Green and White
(c) Blue and White
(d) Blue and Yellow
View AnswerAns: (c)
According to the question,
Green = Blue
Black = Red
White = Yellow
Purple = Orange
The colour of grass is green, and of mango is yellow.
Science Section
Q11: Which of the following options is not an example of traditional method of irrigation?
(a) Pulley system
(b) Chain pump
(c) Drip system
(d) Lever system
Ans: (c)
Option c is not an example of traditional method of irrigation. Drip system or drip irrigation has been popular in recent times only. It is a form of irrigation that saves water and fertiliser by allowing water to drip slowly to the roots.
Q12: Which of the following is an example of microorganism that is used in the preparation of ice creams and jellies?
(a) Gelidium
(b) Virus
(c) Anabena
(d) Rhodomenia
View AnswerAns: (a)
Agar, a jelly-like substance obtained from a type of algae (Gelidium), is used in the preparation of ice creams and jellies.
Q13: Which process is known as carbonisation?
(a) Conversion of dead vegetation into coal
(b) Melting of iron
(c) Burning of tar
(d) Fossilisation of dead plants and animals
View AnswerAns: (a)
About 300 millions year ago, dense forest in low lying lands of the earth got buried because of many natural processes. In a due course of time, they sank deeper and deeper. Beneath the earth, under the geothermal conditions of high pressure and temperature, they slowly converted into coal.
This slow process of conversion of dead vegetation into coal is called carbonisation.
Q14: Read the given statements and select the correct option.
Statement (I): Kerosene oil and wood do not catch fire on their own at room temperature.
Statement (II): A combustible material cannot catch fire as long as the temperature is lower than its ignition temperature.
(a) Both statements (I) and (II) are true and statement (II) is the correct explanation of statement (I).
(b) Both statements (I) and (II) are true but statement (II) is not the correct explanation of statement (I).
(c) Statement (I) is true and statement (II) is false.
(d) Both statements (I) and (II) are false.
View AnswerAns: (a)
The ignition temperature of a substance is the minimum temperature that is required to start or cause combustion. The ignition temperature is also known as the ignition point. It is the temperature at which any substance may catch fire and start burning.
Q15: Fill in the blanks with the most appropriate option.
If a guitar string is pulled strongly, its amplitude of vibration (i) ______ and the note heard is ______ (ii). If it is pulled lightly, its amplitude of vibration ______ (iii) and the note heard is ______ (iv).
(a) (i)-Increases (ii)-Louder (iii)-Increases (iv)-Louder
(b) (i)-Decreases (ii)-Softer (iii)-Decreases (iv)-Softer
(c) (i)-Increases (ii)-Louder (iii)-Decreases (iv)-Softer
(d) (i)-Decreases (ii)-Softer (iii)-Increases (iv)-Louder
View AnswerAns: (c)
Loudness of a sound depends on the amplitude of the sound wave. When amplitude increases, loudness also increases and vice-versa. When we pull the string of a guitar strongly, the string displaces more. Hence, its amplitude of vibration increases and the note heard is louder. Also, when we pull the string of a guitar lightly, the string displaces less. Hence, its amplitude of vibration decreases and the note heard is softer.
Q16: Read the given statements and select the correct option. Statement 1: Electric current can cause or accelerate chemical changes. This property of current is known as the chemical effect of electric current. Statement 2: A solution of cane sugar permits electric current to flow through it.
(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.
View AnswerAns: (c)
- Statement 1 is true because electric current indeed can cause chemical changes, which is referred to as the chemical effect of electric current.
- Statement 2 is false because a solution of cane sugar does not conduct electricity; it is a non-electrolyte.
- Thus, the correct option is that Statement 1 is true but Statement 2 is false.
- This means that while electric current can cause chemical changes, cane sugar solutions do not allow current to pass through.
Q17: How is lightning useful to us?
(a) It helps in nitrogen fixation, which promotes plant growth.
(b) Ozone is formed which prevent ultraviolet rays falling on the earth.
(c) It helps in the evolution of a new species.
(d) All of the above
View AnswerAns: (d)
All of the given statements are uses of lightning.
Q18: Five balls numbered 1 to 5 are suspended using separate threads. Pairs (1, 2), (2, 4), (4, 1) show electrostatic attraction while pairs (2, 3) and (4, 5) show repulsion. Then, ball 1 must be
(a) Neutral
(b) Negatively charged
(c) Positively charged
(d) Electrically inactive
View AnswerAns: (a)
- Ball 1 is involved in attraction with balls 2 and 4, indicating it has a neutral charge or is positively charged.
- However, since ball 2 is repelling ball 3, it must be negatively charged. This means ball 1 cannot be negatively charged.
- Since ball 1 attracts both balls 2 and 4, it must be neutral to not affect the charge of ball 2.
- Thus, the only logical conclusion is that ball 1 is neutral.
Q19: Earthquakes at two places M and N were measured as 2 and 4. How is the magnitude and their destructive energy at M and N related?
(a) Tremor at N is strong as that at place M.
(b) Tremor at N is four times stronger than that at place M.
(c) Tremor at N is 100 times stronger than that at place M.
(d) Tremor at N is 1000 times stronger than that at place M.
View AnswerAns: (c)
Tremor at N is 100 times stronger than that at place M.
Q20: Consider the following statements and select the option which correctly identifies true (T) and false (F) ones.
(i) North-East India receives very little rain throughout the year, so we can say that climate in North-East India is hot and dry.
(ii) Thick layer of subcutaneous fat, thick skin and a dense feather cover in polar birds like penguins protect them from severe cold weather.
(iii) Polar animals need to conserve water due to water scarcity.
(iv) As we move higher up from sea level temperature becomes lower.
(a) FFTT
(b) FTFT
(c) FFTF
(d) TTFT
View AnswerAns: (c)
North-East India receives rain for a major part of the year. Therefore, the climate of the North-East is wet. Polar animals do not need to conserve water in their bodies as they are living in cold environment.
Q21: Study the characteristics of an animal X given below.
(i) Red eyes
(ii) Very good eye sight.
(iii) Sticky pads on its feet.
(iv) Get food from fruits.
Which of the above characteristics does not belong to red-eyed frog?
(a) I
(b) II
(c) III
(d) IV
View AnswerAns: (d)
Red eyed frog have red eyes, very good eye-sight and sticky pads on its feet.
Q22: Study the given flow chart and identify X and Y. 
(a) X = Pacific ocean, Y = Arabian sea
(b) X = Arabian sea, Y = Bay of Bengal
(c) X = Pacific ocean, Y = Bay of Bengal
(d) X = Indian ocean, Y = Pacific ocean
View AnswerAns: (b)
Southwest monsoon originates from Arabian sea and Bay of Bengal.
Q23: The water heater of a shower is connected through a circuit breaker. The purpose of the circuit breaker is:
(a) To cut off the current when the shower is turned off
(b) To cut off the current when the water heater is switched off
(c) To cut off the current when there is a short circuit
(d) To cut off the current when the water reaches the preset temperature
View AnswerAns: (c)
- Function of a circuit breaker: It is designed to protect electrical circuits from damage.
- Short circuit protection: When there is a fault, like a short circuit, the circuit breaker will automatically cut off the current.
- This prevents overheating and potential fires, ensuring safety.
- Options (a), (b), and (d) do not accurately describe the primary function of a circuit breaker.
Q24: A pendulum X makes 30 complete oscillations in 15 seconds. If another pendulum Y makes 19 complete oscillations in 9 seconds, select the incorrect statement(s):
(a) (ii) and (iii) only
(b) (iii) only
(c) (ii), (iii) and (iv) only
(d) (i), (ii) and (iv) only
View AnswerAns: (d)
- The time period of a pendulum is influenced by the length of the string and the mass of the bob.
- Since pendulum Y has a shorter period than pendulum X, it means that pendulum Y swings faster.
- Statement (i) is incorrect because a longer string results in a longer period, not shorter.
- Thus, the correct answer includes statements that are incorrect, which are (i), (ii), and (iv).
Q25: A glass container with an inner depth of 28 cm is placed on a table. A student begins to pour water (m = 4/3) into it while observing the water's surface from above. When he perceives that the container is half full and half empty, he ceases to pour water. What is the actual height of the water in the container?
(a) 16 cm
(b) 9.3 cm
(c) 14 cm
(d) 30 cm
View AnswerAns: (a)
- The inner depth of the container is 28 cm.
- The student perceives the container as half full when he stops pouring.
- Since he sees it as half full, the actual height of the water is half of 28 cm, which is 14 cm.
- However, due to the optical illusion caused by the shape of the container, he stops at 16 cm instead of 14 cm.
Q26: Read the given statements carefully and select the correct option.
Statement 1: Petrol condenses near the top of the fractionating column compared to diesel oil.
Statement 2: Petrol is more volatile than diesel oil.
(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) Both statement 1 and statement 2 are false.
View AnswerAns: (a)
- Statement 1 is correct because petrol, being lighter, condenses at a higher point in the fractionating column than diesel oil.
- Statement 2 is also correct as petrol is indeed more volatile, meaning it evaporates more easily than diesel oil.
- Since both statements are true and statement 2 explains why statement 1 is true, option (a) is the correct choice.
- This understanding of volatility and condensation is crucial in the process of separating different components in crude oil refining.
Q27: Rahul took two liquids labelled A and B using a bulb to observe the conduction of electricity. On passing electric current, the bulb glows brightly in liquid B but glows dimly in liquid A.
(a) Liquid A is a good conductor of electricity.
(b) Liquid B is a good conductor of electricity.
(c) Both liquids are good conductor of electricity.
(d) Both the liquids are bad conductor of electricity.
View AnswerAns: (b)
The bulb glow brightly in the liquid which is a good conductor of electricity.
Q28: In a dry cell, a metal container of zinc and a carbon rod acts as electrode. Which of them is a positive or negative electrode?
(a) Zinc acts as negative electrode and carbon rod act as positive electrode.
(b) Zinc acts as positive electrode and carbon rod act as negative electrode.
(c) Zinc and carbon rod both acts as positive electrode.
(d) Zinc and carbon rod both acts as negative electrode.
View AnswerAns: (a)
A dry cell is made of a zinc container which acts as the negative electrode and a carbon rod as the positive electrode.
Q29: Choose the correct statement about galvanic cell.
Statement 1: The positively charged electrode is called cathode
Statement 2: The negatively charged electrode is called anode
(a) Statement 1 is correct.
(b) Statement 2 is correct.
(c) Both statements are correct.
(d) Both statements are incorrect.
View AnswerAns: (c)
In galvanic (voltaic) cell, the positive electrode is called cathode and the negative electrode is called anode.
Q30: During the refining process of petroleum, several fractions are produced. The following fractions are listed:
(i) Petrol
(ii) Heavy oil
(iii) Kerosene
(iv) Diesel
(v) Petroleum gas.
Arrange these fractions in order of their boiling points from highest to lowest and choose the correct option.
(a) (ii) > (iv) > (iii) > (i) > (v)
(b) (v) > (i) > (iii) > (iv) > (ii)
(c) (i) > (iii) > (v) > (ii) > (iv)
(d) None of the above is the correct order.
View AnswerAns: (a)
- The correct order of boiling points from highest to lowest is Heavy oil > Diesel > Kerosene > Petrol > Petroleum gas.
- Heavy oil has the highest boiling point, followed by Diesel, then Kerosene, with Petrol having a lower boiling point, and finally Petroleum gas, which has the lowest boiling point.
- This order is important in the refining process as it helps in separating these fractions based on their boiling points.
- Thus, option (a) correctly represents the decreasing order of boiling points for these petroleum fractions.
Q31: Choose the correct option from the following by observing the given statements.
Statement I: The diesel is obtained from natural resource of petroleum.
Statement II: Due to natural processes like flooding, the forest got buried under the soil and under high pressure and high temperature, dead plants got slowly converted to petroleum.
(a) Statement I and II are true and statement II is not the correct explanation of statement I.
(b) Statement I is false and statement II is true.
(c) Statement I and II are true and statement II is the correct explanation of statement I.
(d) Statement I is true and statement II is false.
View AnswerAns: (c)
Petrol and diesel are obtained from a natural resource called petroleum.
Coal is formed from remains of plants buried beneath the crust of the earth. Over time, geological actions change the chemical and physical properties of the remains to create a solid material, i.e., coal.
Q32: Which of the following is incorrect?
(i) Bitumen, a petroleum product is used for melting the roads.
(ii) The coal-tar products are used as starting materials for manufacturing various substances like many chemical fertilizers.
(iii) Paraffin wax is used for making vaseline. (iv) CNG can be used directly for burning in home and industries.
(a) (i)
(b) (iii)
(c) (ii)
(d) (iv)
View AnswerAns: (c)
Coal tar is a black coloured thick liquid with unpleasant smell and is obtained from coal. The by-products obtained from coal tar are used as starting materials in the manufacturing of synthetic dyes, perfumes, drugs, explosives.
Q33: Which of the following statements are accurate?
(I) Non-renewable resources are those which once used up cannot be replaced within a reasonable period of time.
(II) Coal and natural gas are inexhaustible natural resources.
(III) CNG is more polluting than petrol.
(IV) The high temperature and high pressure inside the earth slowly converts the buried vegetation into coal.
(a) I and II only
(b) II and IV only
(c) I, III and IV only
(d) I and IV only
View AnswerAns: (d)
- Non-renewable resources are defined as those that cannot be replenished in a short time after being used up, which makes statement I correct.
- Statement II is incorrect because coal and natural gas are not inexhaustible; they are finite resources.
- Statement III is also incorrect as CNG (Compressed Natural Gas) is generally considered to be less polluting than petrol.
- Statement IV is correct; the process of converting buried vegetation into coal occurs under high temperature and pressure over time.
Q34: X is a kharif crop whereas Y is a rabi crop. Select the option that correctly identifies X and Y.
(a) Cotton - Mustard
(b) Groundnut - Wheat
(c) Pea - Gram
(d) Wheat - Paddy
View AnswerAns: (a)
- Kharif crops are typically sown with the onset of the monsoon and harvested in the autumn. Cotton is a well-known kharif crop.
- Rabi crops are sown in the winter and harvested in the spring. Mustard is a common rabi crop.
- Thus, the correct pairing is Cotton for kharif and Mustard for rabi.
- The other options do not correctly match the kharif and rabi classifications.
Q35: Abida and Ramesh were conducting an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick on the yellow part of the candle flame. Ramesh kept the beaker on the outermost part of the flame. Which of the following options is TRUE according to the situation?
(a) Abida has kept the beaker in the non-luminous zone of the flame.
(b) Ramesh's beaker will be heated faster
(c) Abida's beaker will be heated faster
(d) Ramesh has kept the beaker in the luminous zone of the flame.
View AnswerAns: (b)
- The non-luminous (outermost) part of the flame is the hottest, on account of complete combustion of the fuel in this zone.
- The luminous (Yellow, middle) part of the flame is less hot due to incomplete combustion.
- Since Abida has kept the beaker in the luminous zone of the flame, the beaker will take more time to get heated.
- On the other hand, Ramesh has kept the beaker in the non-luminous zone of the flame, so his beaker will be heated in shorter time.
Q36: Rhizome is the primary underground stem that produces buds leading to the growth of new plants. Which of the following contains a rhizome?
(a) Ginger
(b) Garlic
(c) Onion
(d) Carrot
View AnswerAns: (a)
- Rhizome is a type of stem that grows horizontally underground.
- It serves as a storage organ and helps in the propagation of new plants.
- Among the options, ginger is well-known for having a rhizome, which is the part we commonly use in cooking.
- Other options like garlic and onion have bulbs, while carrot is a taproot.
Q37: Which of the following pairs of microorganisms is responsible for cheese production?
(a) Penicillium, Gelidium
(b) Nostoc, Lactobacillus
(c) Streptococcus, Anabaena
(d) Lactobacillus, Streptococcus
View AnswerAns: (d)
- The correct answer is Lactobacillus and Streptococcus, which are essential for cheese making.
- These microorganisms help in the fermentation process, converting lactose into lactic acid.
- This acidification is crucial as it helps in developing the flavor and texture of cheese.
- Other options listed do not play a significant role in cheese production.
Q38: Select the incorrect pairing.
(a) Kanha National Park – Madhya Pradesh
(b) Kaziranga National Park – Assam
(c) Sunderbans National Park – West Bengal
(d) Gir National Park – Jharkhand
View AnswerAns: (d)
- The question asks for the incorrect match of national parks and their respective states.
- Kanha National Park is indeed located in Madhya Pradesh.
- Kaziranga National Park is correctly situated in Assam.
- Sunderbans National Park is accurately found in West Bengal.
- However, Gir National Park is located in Gujarat, not Jharkhand, making option (d) the incorrect match.
Q39: L.P.G is the most common domestic fuel which is stored in cylinders or transported through pipelines.
Which of the following statements about L.P.G is/are incorrect ?
I. It is a foul smelling gas.
II. It is a clean fuel with a high calorific value.
III. It undergoes spontaneous combustion in the gas burners.
IV. It is a mixture of hydrocarbons.
(a) I and II
(b) II and III
(c) II and IV
(d) I and III
View AnswerAns: (d)
- L.P.G is an odourless gas by itself. However, it is mixed with a foul smelling mercaptane gas so that any leakage can be detected by the smell.
- Hence, statement I is incorrect.
- L.P.G undergoes rapid combustion, not spontaneous combustion.
Q40: Refer to the given analogy and select the option that correctly identifies X.
Cockroach : Uricotelic :: X : Ureotelic
(a) Frog
(b) Crocodile
(c) Toucan
(d) Snake
View AnswerAns: (a)
- The analogy compares the excretory methods of two organisms. A cockroach is classified as uricotelic, meaning it excretes waste in the form of uric acid.
- To find X, we need an organism that is ureotelic, which means it excretes waste primarily as urea.
- Among the options, a frog is known to be ureotelic, as it excretes urea, especially in its adult form.
- Other options like crocodiles, toucans, and snakes do not primarily excrete urea, making the frog the correct choice.
Q41: Which of the following sets includes diseases caused by bacteria?
(a) Cholera, Tuberculosis, Malaria, Measles
(b) Smallpox, Tuberculosis, Malaria, Typhoid
(c) Cholera, Tuberculosis, Typhoid, Measles
(d) Cholera, Anthrax, Tuberculosis, Typhoid
View AnswerAns: (d)
- The correct answer is (d) because Cholera, Anthrax, Tuberculosis, and Typhoid are all caused by bacteria.
- Malaria and Measles are not bacterial diseases; Malaria is caused by a parasite and Measles is a viral infection.
- Tuberculosis and Typhoid are well-known bacterial infections, while Cholera is caused by the bacterium Vibrio cholerae.
- Anthrax is caused by the bacterium Bacillus anthracis, making option (d) the only one that lists only bacterial diseases.
Q42: Match the following:
(a) 1 – a, 2 – b, 3 – c, 4 – d, 5 – e
(b) 5 – a, 4 – b, 3 – c, 2 – d, 1 – e
(c) 1 – d, 2 – a, 3 – b, 4 – c, 5 – e
(d) 2 – b, 3 – c, 4 – a, 5 – e, 1 – d
View AnswerAns: (c)
- The metal used for making engines is iron.
- The metal used for making electric wires is copper, as copper is light in weight and also a good conductor of electricity.
- The substance used as a fuel is carbon.
- The metal used in thermometers is mercury.
- The metal used in aircraft is titanium.
Q43: Food is initially taken in by which part of the stomach in ruminants?
(a) Reticulum
(b) Rumen
(c) Abomasum
(d) Omasum
View AnswerAns: (b)
- The rumen is the first chamber of the stomach in ruminants, where food is stored and begins to ferment.
- Ruminants, like cows and sheep, have a unique digestive system that allows them to break down tough plant materials.
- After the rumen, food moves to the reticulum, then to the omasum, and finally to the abomasum for digestion.
- This process helps them extract maximum nutrients from their food.
Q44: Which of the following processes is not part of the primary treatment of wastewater?
(a) Formation of activated sludge through aerobic bacteria
(b) Separation of large solids using strainers
(c) Settling of suspended solids in the settlement tank
(d) Removal of floating materials using a skimmer
View AnswerAns: (a)
- The primary treatment of wastewater focuses on removing large solids and floating materials.
- Formation of activated sludge is a process that occurs in secondary treatment, where bacteria break down organic matter.
- In primary treatment, methods like separation of large solids and settling of suspended solids are used.
- Thus, option (a) is the correct answer as it does not belong to primary treatment.
Q45: In which of the following options does the applied force cause a change in the shape of an object?
(a) Squeezing of a plastic bottle
(b) Pressing clay between hands
(c) A drawer is pulled to open it
(a) Only (a)
(b) Both (a) and (b)
(c) Only (c)
(d) Both (b) and (c)
View AnswerAns: (b)
Both, squeezing of a plastic bottle, and pressing clay between the hands changes the shape of objects.
Achievers Section
Q46: Ankit proposed measuring the speed of sound with the following arrangement. He is positioned 400 m away from a large wall and fires a starting pistol. A fellow student beside him starts the timer when she hears the pistol and stops it when she hears the echo. The times recorded after Ankit repeated the experiment three times are 2.42 s, 2.53 s, and 2.52 s. Based on this experiment, what is the average speed of sound?(a) 330 m/s
(b) 341 m/s
(c) 321 m/s
(d) 350 m/s
View AnswerAns: (c)
- To find the average speed of sound, we first need to calculate the total time taken for the sound to travel to the wall and back.
- The average time recorded is (2.42 + 2.53 + 2.52) / 3 = 2.47 seconds.
- The sound travels to the wall and back, so the total distance is 2 x 400 m = 800 m.
- Using the formula speed = distance/time, we get speed = 800 m / 2.47 s ≈ 323.5 m/s, which rounds to 321 m/s.
Q47: Match the following petroleum product with its uses.
(a) (i) – S, (ii) – P, (iii) – Q, (iv) – R
(b) (i) – P, (ii) – S, (iii) – Q, (iv) – R
(c) (i) – S, (ii) – Q, (iii) – P, (iv) – R
(d) (i) – S, (ii) – P, (iii) – R, (iv) – Q
View AnswerAns: (a)
- Petrol is used as a fuel in motor car, aviation and as a solvent for dry cleaning.
- Diesel is used as a fuel for heavy vehicles such as trucks, rail engines, for small vehicles such as jeep car, for jet air-crafts, small generators, etc.
- Kerosene is used as a fuel for stoves, jet air-crafts and lamps, etc.
- Bitumen is used in making of paints and roads, etc.
Q48: Match the following:
(a) 1 - x, 2 - z, 3 - w, 4 - y
(b) 1 - x, 2 - z, 3 - y, 4 - w
(c) 1 - z, 2 - x, 3 - w, 4 - y
(d) 1 - x, 2 - w, 3 - z, 4 - y
View AnswerAns: (a)
- Drag - The frictional force exerted by fluids
- Rolling friction - The force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface
- Static friction - The friction that exists between a stationary object and the surface on which it is resting
- Sliding friction - The resistance created by any two objects when sliding against each other
Q49: Following are given some properties of metals. Select the option which shows the correct group of properties.
Statements:
(i) At room temperature, all the metals are solid except mercury which is a liquid.
(ii) Sodium and potassium are metals and soft like wax.
(iii) Metals have a brilliant shine which is referred to as the metallic lustre.
(iv) Metals are not malleable.
(v) Metals can be drawn into very thin wires.
(a) (iii), (iv), (v)
(b) (i), (iii), (iv), (v)
(c) (i), (iii), (v)
(d) (i), (ii), (iii) and (v)
View AnswerAns: (d)
The properties of solids are as follows:-
- At room temperature, all the metals are solid except mercury which is a liquid.
- Sodium and potassium are metals and are soft like wax.
- Metals have a brilliant shine showing a metallic lustre.
- Metals are ductile.
- Metals can be drawn into very thin wires.
Hence, (i), (ii), (iii) and (v) are the correct properties.
The statement (iv) is incorrect because metals are malleable and can be beaten into sheets.
Q50: In which of the following processes is the food material exposed to high energy radiation in order to preserve it?
(a) Bottling
(b) Canning
(c) Dehydration
(d) Irradiation
View AnswerAns: (d)
Irradiation is a modern method of food preservation. By the term irradiation, we mean the process of exposing the food material to high energy radiation. The food material to be preserved is exposed to gamma rays or x-rays. These powerful radiation completely destroy the harmful micro-organisms present in the food material.
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