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UPSC > Everyday Science

Explore popular questions from Everyday Science for UPSC. This collection covers Everyday Science previous year UPSC questions hand picked by experienced teachers.

Q 1.

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An astronaut orbiting the earth in a circular orbit 120 km above the surface of earth, gently drops a spoon out of the space ship. The spoon will

A

fall vertically down to the earth

B

move towards the moon

will move along with the space ship

D

will move in an irregular way and then fall down to earth

Explanation

When spoon is dropped gently, its tangential speed is equal to the speed of spaceship, and so it revolves like a satellite.

Q 2.

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Which of the statements given below is/are correct? Permanent hardness of water is due to the presence of soluble.
1. chloride of calcium
2. bicarbonate of calcium
3. sulphate of magnesium
4. bicarbonate of magnesium
Select the correct answer using the codes given below.

A

1 only

1 and 3

C

2 and 4

D

1,2 and 3

Explanation

Chlorides and sulphates of calcium and magnesium are responsible for permanent hardness of water.
Note: Bicarbonates are responsible for temporary hardness of water.

Q 3.

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Why ethylene dibromide is added to petrol -
1. It increases the octane number of fuel
2. It helps in elimination of lead oxide
3. It removes the sulphur compound in petrol
4. It serves as a substitute of tetraethyl lead

A

1 and 2

B

2 and 3

C

1 only

2 only

Explanation

Lead oxide deposit is harmful to engine life. Thus a small amount of ethylene dibromide is added to petrol for simultaneous removal of lead oxide.

Q 4.

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Refrigeration helps in food preservation by

A

killing the germs

reducting the rate of biochemical reactions

C

destroying enzyme action

D

scaling the food with a layer of ice

Explanation

Refrigeration helps in food preservation by reducing. The rate of biochemical reactions.

Q 5.

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Earthquake (shock) waves are

A

infrasonic waves

B

ultrasonic waves

seismic

D

infrared waves

Explanation

An Earthquake is the result of a sudden release of energy in the Earth’s crust that creates seismic waves.

Q 6.

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Fat can be separated from milk in a cream separation because of

A

cohesive force

B

gravitational force

centrifugal force

D

centripetal force

Explanation

Centrifugal force separates fat from milk.

Q 7.

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Raw mangoes shrivel when pickled in brine. The phenomenon is associated with

osmosis

B

reverse osmosis

C

increase of surface tension of fluid

D

decrease of surface tension of fluid

Explanation

Raw mangoes shrivel when pickled in brine due to osmosis i.e. How of water from higher concentration to lower concentration through a semi-permeable membrane.

Q 8.

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Half portion of a rectangular piece of ice is wrapped with a white piece of cloth w hile the other half with a black one. In this context, which one among the follow ing statements is correct?

Ice melts more easily under black wrap

B

Ice melts more easily under white w rap

C

No ice melts at all under the black wrap

D

No ice melts at all under the white wrap

Explanation

Ice under black wrap will melt easily because dark colour (black) absorbs the most of light energy falling on it.

Q 9.

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Mr X was advised by an arehitect to make outer walls of his house with hollow' bricks. The correct reason is that such walls

A

make the building stronger

help keeping inside cooler in summer and warmer in winter

C

prevent seepage of moisture from outside

D

protect the building from lightning

Explanation

The hollow bricks provide thermal insulations; the air in hollow' bricks, does not allow' outside heat or cold in the house to go out or come in the house. So, it keeps house cool in summer and warm in winter.

Q 10.

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If a ship moves from freshwater into seawater, it will

A

sink completely

B

sink a little bit

rise a little higher

D

remain unaffected

Explanation

When a body is immersed in a fluid, the fluid exerts an upward force on it, called buoyant force.
and buoyant force x density of fluid.
As the density of sea water is higher than that of the fresh water.
So extra buoyant force and ship will rise a little higher.

Q 11.

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The cat can survive fall from a height much more than human or any other animal. It is because the cat

can immediately adjust itself to land on all four paws and bend the legs to absorb the impact of falling

B

has clastic bones

C

has thick and elastic skin

D

also gets injury equally with other animals, but has tremendous endurance, resistance and speedy recovery

Explanation

As the cat falls from a height, it bends the legs to absorb the impact of falling and immediately adjust itself.

Q 12.

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Fire fly gives us cold light by virtue of the phenomenon of fluorescence

A

phosphorescence

B

chemiluminescence

effervescence

Explanation

Fire fly gives us cold light due to chemiluminescence i.e. light produced by chemical reaction.

Q 13.

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The best colours for a sun umbrella will be

A

black on top and red on inside

B

black on top and white on inside

C

red on top and black on inside

white on top and black on inside

Explanation

As white colour reflects all the components of white light and black colour absorbs all the components of white light. So, the best colours for a sun umbrella, white on top and black on inside.

Q 14.

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When ice melts, its

volume decreases

B

volume increases

C

volume and mass both decrease

D

volume decreases while mass increases

Explanation

When ice melts its density increases i.e. its volume decreases. Mass is a invariant quantity.

Q 15.

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When deep sea fishes are brought to the surface of the sea, their bodies burst. This is because the blood in their bodies flows at very

high speed

B

high pressure

C

low speed

D

low pressure

Explanation

When deep sea fishes are brought to the surface of the sea, their bodies burst, this is because the blood in their bodies flows at very high speed.

Q 16.

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By what mechanism does scent spread all over the room if the lid is opened?

A

Pressure in the bottle

B

Compression from the bottle

Diffusion

D

Osmosis

Explanation

Diffusion refers to the process by which molecules intermingle as a result of their kinetic energy of random motion.

Q 17.

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When an incandescent electric bulb glows

A

the electric energy is completely converted into light

the electric energy is partly converted into light energy and partly into heat energy

C

the light energy is converted into electric energy

D

the electric energy is converted into magnetic energy

Explanation

When current flows through the filament of incandescent electric bulb, it gets heated up. Soon it becomes white hot and starts emitting light.

Q 18.

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In cricket match, while catching a fast moving ball, a fielder in the ground gradually pulls his hands backwards with the moving ball to reduce the velocity to zero. The act represents |

A

Newton’s first law of motion

Newton’s second law of motion

C

Newton’s third law of motion

D

Law of conservation of energy

Explanation

We know from Newton’s second law of motion
dP
Fexl = — when di is more Fcxt will be less.
The greater the rate of change of momentum, the greater is the force and vice-versa.

Q 19.

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Two layers of a cloth of equal thickness provide warmer covering than a single layre of cloth with double the thickness. Why?

Because of the air encapsulated between two layers

B

Since effective thickness of two layers is more

C

Fabric of the cloth plays the role

D

Weaving of the cloth plays the role

Explanation

Two layers of a cloth are wanner because air trapped between the layers acts as thermal insulator restricting the heat transfer.

Q 20.

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What is the purpose of adding baking soda to dough? To generate moisture

A

To generate moisture

B

To give a good flavor

C

To give good color

To generate carbon dioxide

Explanation

Baking soda has sodium bicarbonate as the chief constituent. It decomposes on heating giving carbon dioxide. This causes dough, cakes, biscuits etc. to expand and become light.

Q 21.

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Match List I with List II and select the correct answer using the codes given below the Lists. List I List II Industries in which largely (Mineral) ' used) A. Limestone 1 Cement B. Copper 2 Electrical goods C. Bauxite 3 Manufacture of aeroplanes D. Manganese 4 Steel Codes A B C D

A

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

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

C

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

D

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

Explanation

Alloy Constituent
Solder Lead and tin
Brass Copper and zinc
Bronze Copper and tin
Steel Iron and carbon

Q 22.

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Which one of the following is not needed in a nuclear fission reactor?

A

Moderator

B

Coolant

Accelerator

D

Control device

Explanation

Substances like graphite and heavy water are used as moderator to slow dow n the speed of neutrons. Cd or B are used as control rods to control rate of fission by absorbing neutrons.

Q 23.

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When items or jewellery made of metals such as copper or nickel are placed in a solution having a salt of gold, a thin film of gold is deposited by

A

cooling to below 0°C

B

heating above 100°C

passing an electric current

D

just keeping it for 10 min

Explanation

The process of depositing a thin layer of one metal over the surface of other metal by the process of electrolysis is known as electroplating. Hence, when items or jewellery made of metals such as copper or nickel are placed in a solution having a salt of gold, a thin film of gold is deposited by passing an electric current.

Q 24.

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Which one among the following is a sin smelling agent added to LPG cylinder to help the detection of gas leakage?

A

Ethanol

Thioethanol

C

Methane

D

Chloroform

Explanation

Ethyl mercaptan or thioethanol (C2H5SH) is added during filling of LPG cylinders. Il is a strong smelling compound and help in the detection of gas leakage.

Q 25.

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A close bottle containing water at room temperature was taken to the Moon and then the lid is opened. The water will

freeze

B

boil

C

decompose into oxygen and hydrogen

D

not change at all

Explanation

The water will freeze because on Moon the temperature is below the freezing point i.e., very low.