Science Olympiad Previous Year Paper - 3 | Science Olympiad Class 7 PDF Download

Ans: (b)

• The pattern involves a sequence of numbers where each number follows a specific rule.
• In this case, the missing number is determined by the pattern established by the other numbers.
• After analyzing the sequence, it becomes clear that the correct number to fit the pattern is 42.
• This number maintains the consistency of the pattern, making it the right choice.

Ans: (c)

• Rohan starts by walking 7 km South.
• Then, he turns right, which means he is now facing West and walks 3 km.
• Next, he turns left, which means he is now facing South and walks 10 km.
• After these movements, Rohan is still facing South.

Ans: (b)

• To decode the word BEAR, we need to find the corresponding numbers for each letter based on the given codes.
• From BAND: B = 2, A = 5, N = 7, D = 3.
• From READ: R = 4, E = 1, A = 5, D = 3.
• Now, for BEAR: B = 2, E = 1, A = 5, R = 4.
• Putting these together, BEAR is coded as 2154.

Ans: (c)

The pattern is + 2, + 4, + 2, + 4, ..... So, the missing term = 25 + 4 = 29. 

Ans: (b)

• Puneet refers to his brother's father's wife, which is Puneet's mother.
• Since Sneha is the only daughter of Puneet's mother, she must be Puneet's sister.
• This means that Sneha and Puneet share the same parents, making them siblings.
• Thus, the correct relationship is that Sneha is Puneet's sister.

Ans: (d)

In the given word PROFESSOR, the following pattern is used:

P – 1 = O

R + 1 = S

O – 1 = N

F + 1 = G

E – 1 = D

S + 1 = T

S – 1 = R

O + 1 = P

R – 1 = Q

Similarly, ALLOWED will be coded as follows:

A – 1 = Z

L + 1 = M

L – 1 = K

O + 1 = P

W – 1 = V

E + 1 = F

D – 1 = C

Ans: (c)

• The correct sequence starts from the smallest unit to the largest. Room is part of a House, which is located on a Street. Several houses make up a Town, and multiple towns form a District.
• Thus, the logical order is Room (4), House (1), Street (2), Town (3), and District (5).
• This means the correct arrangement is 4, 1, 2, 3, 5.

Ans: (b)

• First, replace the symbols: A is '+', B is '–', and C is '×'.
• This means we need to calculate (14 + 10) – (14 × 2).
• Calculate 14 + 10, which equals 24.
• Next, calculate 14 × 2, which equals 28.
• Now, subtract: 24 – 28 = –4.

Thus, the final answer is –4.

Ans: (b)

The given figure follows a pattern as given below:

7 x 5 = 35 – 5 = 30

9 x 4 = 36 – 4 = 32

6 x 3 = 18 – 3 = 15

Therefore, the missing number is 15.

Ans: (c)

• Rashmi is initially 12th from the top.
• When she moves down by 3 places, her new position is 15th from the top.
• She is now 5th from the bottom, which means there are 4 students below her.
• So, the total number of students is 15 (her new position from the top) + 4 (students below her) = 19.

Ans: (a)

Polar bear has long, curved and sharp claws, which help it walk on ice.

Ans: (a)

If bulb A is fused then no current will flow in wire connecting A, B, D , Hence non of B and D will glow. only C will glow.

Ans: (b)

The wheel of cycle will exert a backward force on the ground, as a result of which the ground will exert an equal and opposite force on the cycle. This reaction force is responsible for the upward moment of the bicycle.

Ans: (c)

• Earthed appliances are designed to ensure safety by directing any stray electrical current safely into the ground.
• This process helps to prevent electric shocks to users by minimizing the risk of current leakage.
• While other options mention issues like overloading or fuse blowing, they do not address the primary safety concern.
• Thus, the correct answer is that earthing is crucial to prevent the leakage of current and reduce the risk of electric shock.

Ans: (a)

In geyser heating is done by by convection , while in other three heat is transfer in the form of electromagnetic radiation.

Ans: (d)

The image formed by a plane mirror is of the same size as that of the object, left-right inverted, and erect and virtual.

Ans: (d)

Punjab is not prone to cyclone as it is not a coastal state.

Ans: (a)

A convex lens is used as a magnifying glass. The convex lens bends the parallel rays so that they converge and create a virtual image on our eyes retinas. That virtual image on our retinas appears larger than the real object due to principles of geometry.

Ans: (d)

• Since the aqueous solution of the substance turns blue litmus red, it is an acid.
• Acids remain colourless with phenolphthalein.

Hence, option (d) is correct.

Ans: (c)

• Increased wind speed is accompanied by increase in air pressure is incorrect because as wind speed increases, the pressure actually decreases in the area of high wind.
• Warm air is indeed lighter than cold air, which is why it rises.
• Air does expand when heated and contracts when cooled, which is a basic principle of physics.
• When there is a greater difference in pressure between two areas, it causes air to move faster, creating wind.

Ans (d)

Stomata are responsible for gaseous exchange occurring during photosynthesis and respiration. Loss of water during transpiration also occurs through stomata.

Ans: (b)

• The change from raw egg to boiled egg is a permanent transformation. Once an egg is boiled, it cannot return to its original raw state.
• In contrast, changes like wet clothes to dry clothes or cold water to hot water can be reversed.
• Similarly, a straight string can be coiled and then straightened again, making those changes reversible.
• Thus, the only irreversible change among the options is the transformation of a raw egg into a boiled egg.

Ans: (c)

• Statement 1 is accurate because acids do indeed produce hydrogen ions when they dissolve in water, which is a defining characteristic of acids.
• Statement 2 is incorrect as acids typically have a sour taste, not a bitter one. For example, lemon juice is acidic and tastes sour.
• Thus, the correct choice is that statement 1 is true while statement 2 is false.

Ans: (a)

Camels have thick fur. They excrete very small amount of urine and dry dung which help them to conserve water. There's no evidence, though, that camels can store water for long periods of time anywhere in their bodies. Camels store fat in their humps, not water. They can very efficiently conserve water but not store it. Rather than directly storing water, camels are built for adapting to the scarcity of water.

Ans: (b)

• Substance U is described as hard, which fits with diamond as it is one of the hardest materials.
• Substance V is transparent, and clear glass is a perfect example of this.
• Substance W sinks in water, which is true for a stone as it is denser than water.
• The other options do not match all three characteristics of U, V, and W.

Ans: (a)

• Statement I is incorrect because during a chemical change, new substances are formed.
• Statement II is true as heat or light can be released or absorbed in a chemical change.
• Statement III is true since new substances with different properties are indeed created.
• Statement IV is incorrect because most chemical changes are not reversible.

Ans: (d)

• Sedimentationdecantation are methods used to separate mixtures based on the different densities of their components.
• In this case, chalk powder mixed with water will settle at the bottom when left undisturbed, allowing the clear water to be poured off.
• The other options involve either dissolving or do not settle out, making them unsuitable for this method.
• Thus, the correct answer is chalk powder and water.

Ans: (c)

• A represents gills of fish.
• Gills are well supplied with blood vessels. Diffusion occurs in gills and oxygen diffuses in the blood vessels of fish from gills.
• Gills are projections of skin found in aquatic organisms.
• Gills are used by fish in respiration and not for drinking water.

Ans: (b)

• Ligaments are the tissues that connect bones to each other at joints, providing stability and support.
• They are made of strong, flexible tissue, allowing for movement while keeping the bones in place.
• In contrast, bone marrow is involved in blood cell production, cartilage provides cushioning between bones, and muscle is responsible for movement.
• Thus, the correct answer is ligament, as it specifically serves the function of connecting bones.

Ans: (b)

• Incineration is the most effective method for disposing of biomedical waste, such as used syringes and blood samples.
• This process involves burning the waste at high temperatures, which helps to eliminate harmful pathogens and reduces the volume of waste.
• Other methods like recycling or composting are not suitable for biomedical waste due to the risk of contamination and infection.
• Therefore, incineration is the recommended approach for safe and efficient disposal of such hazardous materials.

Ans: (d)

• Statement 1 is incorrect because cotton fibers are actually separated from the seeds through a process called ginning, not spinning.
• Statement 2 is also incorrect as the process of separating jute fibers from the jute plant is called retting, not combing.
• Since both statements are false, the correct answer is option (d).
• This highlights the importance of understanding the correct processes involved in fiber extraction.

Ans: (a)

• The desert habitat is characterized by animals that are adapted to dry conditions. The Kangaroo rat is indeed a desert dweller, but the Reindeer and Zebra are not. Reindeer are typically found in cold, northern regions, while Zebras inhabit savannas and grasslands.
• In contrast, the other options correctly match animals with their respective habitats: Yaks, Snow leopards, and Mountain goats are all found in mountainous areas; Penguins, Polar bears, and Walruses thrive in polar regions; and Elephants, Giraffes, and Lions are native to grasslands.

Ans: (d)

When winds flow from land to ocean, they are called land breeze. During night, the land cools down faster than the ocean surface. The warmer air from the ocean surface rises up and creates an area of low pressure near the surface. This is filled in by cooler air from the land. This gives rise to the land breeze.

Ans: (a)

• Silk is known as the strongest natural fibre, making it the correct choice.
• The fabric produced from silk is smooth and has a unique lustre, which is a characteristic feature.
• Silk is derived from the cocoon of silkworms, which involves killing the insect to harvest the fibre.
• Other options like cotton and jute do not match the description provided.

Ans: (a)

• The correct path of oxygen during inhalation starts at the nostrils, where air enters.
• It then moves into the nasal cavity, followed by the pharynx.
• From the pharynx, it travels down the trachea, then into the bronchi, and further into the bronchioles.
• Finally, oxygen reaches the alveoli, where gas exchange occurs.

Ans: (a)
Sulphur burns in the presence of oxygen and releases sulphur dioxide gas, which when gets dissolved in water form sulphuric acid. Sulphuric acid is a strong acid, which turns blue litmus paper red.
S + O₂ ® SO₂
SO₂ + H₂O ® H₂SO₄ (Sulphuric acid)

Ans: (d)
All the statements are correct.

Ans: (b)
Bases release hydroxide ion in the solution medium. When bases are dissolved in water, they are known as alkalis.

Ans: (d)
Litmus solution is a purple dye, which is extracted from lichen.

Ans: (a)

• Leguminous plants are those that belong to the family Fabaceae, which includes plants that produce pods.
• From the list, Beans and Gram are leguminous.
• Additionally, Lentil is also a leguminous plant.
• Thus, the total count of leguminous plants in the list is 3: Beans, Gram, and Lentil.

Ans: (d)

• Shearing refers to cutting the fleece of sheep, not cleaning it with soap.
• Reeling is indeed the process of extracting silk fibre from the cocoon.
• Mulberry leaves are the primary food source for silkworms.
• Thus, the correct answer is Both B and C as both statements about reeling and mulberry leaves are accurate.

Ans: (c)

• The tropical rainforest is home to a variety of species, particularly birds and amphibians.
• Among the options, the Macaw (iii) and Toucan (vi) are well-known inhabitants of these forests.
• The Red-eyed tree frog (v) also thrives in this environment, making option (c) correct.
• Other animals listed, like the Elephant (ii) and Seal (iv), are not typically found in tropical rainforests.

Ans: (d)

• Absence of forests leads to a significant rise in CO2 levels in the atmosphere, contributing to climate change.
• Without trees, the natural balance is disrupted, resulting in more frequent floods and droughts.
• Forests are crucial for biodiversity; their loss can lead to the extinction of various species.
• Therefore, the correct answer is that all these consequences will occur if forests are absent.

Ans: (b)

• Statement (a) is true as heart rate refers to how often the heart beats in a minute.
• Statement (b) is incorrect because the correct term for blood flow from the heart to the lungs and back is pulmonary circulation, not systemic circulation.
• Statement (c) is accurate; nephrons do filter blood and eliminate excess substances.
• Statement (d) is also true; if a plant loses water faster than it can absorb it, it will droop.

Ans: (d)

• Horse is known for pulmonary respiration, which means it breathes using lungs.
• In contrast, a leech uses skin for gas exchange, not tracheal respiration.
• A grasshopper has a different system called tracheal respiration, not branchial.
• Fish primarily use gills for breathing, which is not the same as cutaneous respiration.

Ans: (a)

The portion of leaf covered by transparent strip allows sunlight to pass through and hence, photosynthesis occurs there. It will therefore give a positive iodine test for the presence of starch.

Ans: (c)

Step 1: Shearing - It is the first step in the process of obtaining wool from the sheep. The fleece (hair) of sheep is shaved off along with a thin layer of skin.

Step 2: Scouring - Fleece, after shearing, is washed properly to remove dirt and grease.

Step 3: Sorting - After scouring, fleece is sorted according to the texture.

Step 4: Dyeing - After sorting and picking out of burrs, these are dyed in desired colours.

Step 5: Spinning - The fibres are then straightened, combed and rolled into yarn.

Hence, option (c) is correct.

Ans: (a)

(A) When an object repeats its motion after every fixed interval of time, the motion of the object is called periodic motion or oscillatory motion. Swinging of a pendulum is an example of oscillatory motion.
(B) Odometer is a device used to measure the distance covered by a vehicle. (B) shows odometer.
(C) A device used to measure the speed of a vehicle is called speedometer. (C) shows speedometer.
(D) Motion along a straight line is known as rectilinear motion. A boy riding a bicycle is an example of rectilinear motion.

Ans: (b)

• Statement (i) is true because forest fires can indeed be triggered by lightning strikes.
• Statement (ii) is correct as the understorey is the layer of vegetation that grows beneath the forest canopy.
• Statement (iii) is incorrect; without forest cover, soil erosion actually increases due to lack of roots to hold the soil.
• Statement (iv) is true since humans rely on forests for various resources like timber and resin.
• Statement (v) is false; the canopy actually receives the most sunlight compared to other layers.

Thus, the correct statements are (i), (ii), and (iv), making option (b) the right choice.

Ans: (b)

• Budding is a type of asexual reproduction in plants and organisms. It is used by unicellular plants; like yeast. Yeast is a fungus and fungi are also known as non-green plants. The yeast cell produces a bud which gets its own nucleus. The bud develops to a certain size and detaches from the mother cell to produce the new yeast. Picture (A) shows budding in yeast.
• In some simple plants, the plant body is divided into smaller fragments. Each fragment then develops into a new plant. This is called fragmentation. It is a type of asexual reproduction in plants and organisms. Example: Spirogyra. Picture (B) shows fragmentation in Spirogyra.
• Special spore-bearing organs are present in some plants; especially in fungi and algae. These are called sporangiophores. The sporangiophore bears spores. The spores germinate to develop a new plant. It is called spore formation. It is a type of asexual reproduction in plants and organisms. Picture (C) shows spore formation in fungi.