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Common Observation MCQs for FPSC, PCS, NTS Competitive Exams

Common Observation MCQs for FPSC, PCS, NTS Competitive Exams
Written by CSS Times

The colour of the sky looks blue because:
(a) Sky is made up of blue colour particles
(b) Blue color of light is of shorter wavelength, so these waves are easily scattered by dust particles and water vapour
(c) Blue colour is more prominent in sunlight
(d) Blue colour is of longer wavelength

Clear nights are colder than cloudy, nights because of:
(a) Conduction
(b) Radiation
(c) Condensation
(d) Insolation
Answer: b

Oil rises up the wick in a lamp because:
(a) Oil is very light
(b) Of the diffusion of oil through the wick
(c) Oil is volatile
(d) Of the capillary action phenomenon
Answer: d

The dress made out of which of the following materials is safe to wear while cooking?
(a) Silk
(b) Cotton
(c) Nylon
(d) Terelene
Answer: b

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Tiredness is felt on the top of the mountains because of:
(a) High temperature
(b) Low temperature
(c) Low pressure outside the body
(d) High pressure outside the body
Answer: c

The wet camel hair, when brushed, cling together due to:
(a) Elasticity
(b) Adhesion
(c) Virosis
(d) Surface tension
Answer: b

Cooking is quicker in a pressure cooker because:
(a) It increases boiling point of water
(b) It increases the temperature of the content
(c) Of the penetrating action of steam
(d) The whole of the heart remains inside
Answer: a

The water in an open pond remains cool even in hot summer because:
(a) Of continuous evaporation of water
(b) Water absorbs heat less rapidly than the atmosphere
(c) Water radiates heat more rapidly than the atmosphere
(d) None of these
Answer: b

Nights are cooler in the deserts because:
(a) Sand radiates heat less quickly as compared to earth
(b) Sand radiates heat more quickly as compared to earth
(c) The sky is generally clear
(d) The sky is generally cloudy
Answer: b

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Clothes keep us warm in winter because they:
(a) Supply heat
(b) Do not radiate heat
(c) Prevent the heat of the body from escaping
(d) None of these
Answer: c

Pressure cooker is fast in cooking rice because:
(a) It lets the steam escape
(b) High pressure raises the boiling point of water
(c) High pressure crushes the hard covering of rice grains
(d) None of these
Answer: b

The tube light is felt cooler than the light from a bulb of the same wattage because the:
(a) Tungsten is not used in the tube
(b) Tube consume less power
(c) Tube is fixed at greater height than the bulb
(d) Surface area of a tube is larger than that of a bulb
Answer: a

When milk is churned, the cream is separated from it due to:
(a) Frictional force
(b) Cohesive force
(c) Gravitational force
(d) Centrifugal force
Answer: d

When a person enters a dark room from bright light, he cannot see anything clearly from some time. Slowly, he starts seeing things. This is because:
(a) The length of lense increase
(b) The iris expands
(c) The iris contracts
(d) The distance between the lens and retina increases
Answer: c

In summer, a cloudy night is hotter than a star lit night because:
(a) Clouds work as a thick blanket and produce heat
(b) Clouds do not allow cold air to reach earth
(c) Clouds prevent the heat radiated by the earth from escaping to the sky
(d) Heat is generated by clouds and radiated back to earth
Answer: c

Food remains unspoilt in a refrigerator for a longer time because:
(a) The antibiotics inside a refrigerator kill bacteria and fungus
(b) Bacteria and fungus can not multiply fast at sufficiently low temperatures
(c) The low temperature inside makes the food shrink and thereby crush the germs
(d) Refrigerator contains food preservatives that get activated at low temperatures
Answer: b

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Thermos flask keeps a liquid hot because:
(a) It has double walls
(b) It has silver coated walls
(c) Heat losses by conduction and radiation are largely prevented
(d) Air between the double walls is removed
Answer: c

When a vehicle passes, TV reception gets distorted. This is because:
(a) Metal reflects radio waves
(b) Spark plug creates electromagnetic disturbances
(c) Passing vehicle affect the sophisticated T.V. components
(d) None of these
Answer: b

Why is it easier to swim in a sea than a river?
(a) Sea water is still while river water in running
(b) Salinity of seawater is more than that of river water
(c) Density of seawater is more than that of river
(d) None of these
Answer: c

The ink from the fountain pen spills out when the pen is carried inside an air borne plane, because:
(a) The atmospheric pressure at high attitude is less compared to what is at the sea level
(b) The atmospheric pressure at high attitude is more than what is at the sea level
(c) The atmospheric pressure is exactly the same as that at the sea level
(d) The atmospheric pressure keeps changing rapidly
Answer: a

It is observed that when glass is heated, it cracks while metal does not which of the following statements explains this phenomenon?
(a) Metal is poor conductor of heat
(b) The expansion of the glass after heating is uniform and therefore it cracks
(c) Glass is poor conductor of heat
(d) In case of glass, the heat is transmitted quickly when it is heated
Answer: c

An ice cube is floating in a glass of water. How will the water level in the glass be affected when the ice cube melts?
(a) It will rise
(b) It will go down
(c) It will remain unchanged
(d) It would first go up but later on it will go down
Answer: c

Railway tracks are banked on curves so that:
(a) The train may not fall down inward
(b) Necessary centrifugal force may be obtained from the horizontal component of the weight of the train
(c) No frictional force may be produced between the track and the wheel
(d) The weight of the train may be reduced
Answer: b

Moon has no atmosphere because:
(a) It is quite for off
(b) It does not have any living being
(c) Its surface is not smooth
(d) Root mean square velocity of all gases is more than their escape velocity on moon’s surface
Answer: d

A corked bottle full of water when frozen will break because:
(a) Glass is a bad conductor of heat
(b) The bottle contracts on freezing
(c) The volume of water increases on freezing
(d) The volume of water decreases on freezing
Answer: c

A ship rises as it enters the sea from a river because the:
(a) Water is sea is hard water
(b) Density seawater is higher than that of the river water
(c) Larger quantity of water in the sea pushes the ship upward
(d) None of these
Answer: b

The stars twinkle in the night because:
(a) They emit light intermittently
(b) The star’s atmosphere absorbs light intermittently
(c) The refractive index of the air in atmosphere fluctuates
(d) The earth’s atmosphere absorbs light intermittently
Answer: c

Why does radio perception improves slightly during night?
(a) Sunlight affects radio broadcast to some extent
(b) The outside noise is reduced very much at night
(c) The magnetic field of the earth acts with reduced intensity during the night thereby reducing its impact on broadcasts
(d) None of these
Answer: a

Small drops of a liquid are spherical in shape because:
(a) The surface energy is minimum for the spherical shape
(b) The surface energy is maximum for the spherical shape
(c) For a given volume, the surface area of a sphere is maximum
(d) None of these
Answer: a

Sun appears radish during the rising and setting time because:
(a) The atmosphere absorbs short wavelengths more than long wavelengths.
(b) High of shorter wavelengths are a scattered to a greater extent than the longer wavelengths by the atmosphere
(c) The atmosphere absorbs long wavelengths more than short wave lengths
(d) None of these
Answer: b

Rainbow is produced by tiny rain drops suspended in front of sun rays as a result of:
(a) Reflection and interference
(b) Refraction and dispersion
(c) Interference
(d) Reflection, refraction and dispersion
Answer: d

Why is the light of ordinary lamp hotter than the tube light?
(a) It is due to incandescence
(b) It gives white light
(c) It has more surface for distribution of energy
(d) It is due to ionization of gases
Answer: a

Why are two blankets warmer than one?
(a) Two blankets have more wool and hence, provide greater warmth
(b) Two blankets enclose air which does not allow the cold to perpetrate
(c) Two blankets compress the air in between the body and the blankets and this compression produces heat
(d) None of these
Answer: b

A fresh egg sinks in pure water whereas it floats in saturated salty water. This is because:
(a) Of higher density of pure water
(b) Of higher density of salty water
(c) Egg shell is made of calcium which is heavier than pure water
(d) The fluid matter inside the egg has the same density as the salty water
Answer: b

Why does the police use dogs for detective work? Because _____
(a) They have sharp eyesight
(b) They can run very fast
(c) They can hear ultrasonic waves
(d) They are easily trainable
Answer: c

The blue colour of the water in the sea is due to:
(a) Reflection of blue sky by seawater and scattering of blue light by water molecules
(b) Reflection of the blue light by the impurities in sea water
(c) Absorption of other colours by water molecules
(d) None of these
Answer: a

A lighted candle gets extinguished when covered with a tumbler because of:
(a) Adequate supply of air
(b) Inadequate supply of air
(c) Presence of non-luminous matter
(d) None of these
Answer: b

A glass chimney stops an oil lamp from smoking because:
(a) It increases the supply of oxygen to the flame by convection
(b) The heat produced ensures complete combustion of carbon particles
(c) Both (a) and (b)
(d) None of these
Answer: c

A greenish yellow colour is seen on a boiled egg. This is due to:
(a) Oxidation of some vitamins in the egg
(b) Oxidation of sulphur in the egg
(c) Formation of some iron compounds
(d) None of these
Answer: c

Microwave links are preferred for telephone because:
(a) Long-distance telephone becomes easier
(b) More telephones can be used
(c) Transmission is easier
(d) Reception is cheaper
Answer: a

If you float on your back, on water, your weight will be:
(a) Less than the weight of water displaced by you
(b) Half of your normal weight
(c) Zero
(d) Equal to your normal weight
Answer: c

Sea water is saltier than rain water because:
(a) Sea animals are salt producing
(b) Rivers wash away salts from earth and pour them into sea
(c) Sea beds have salt producing mines
(d) The air around sea is saltish
Answer: b

Water is a highly effective coolant for a car engine because:
(a) Water is good conductor of heat
(b) Water has very high specific heat capacity
(c) Evaporation of water produces lot of cooling
(d) None of these
Answer: b

Existence on moon is not possible because of:
(a) High pressure
(b) Low pressure
(c) Absence of air
(d) Its weak gravitational power
Answer: d

Air is completely removed from an electric bulb to prevent:
(a) Oxidation of tungsten filament
(b) Bursting of the bulb
(c) Loss of light due to absorption
(d) None of these
Answer: a

The sun rays falling on a thin film of oil spread over a water surface breaks into different colours. This is due to:
(a) Interference
(b) Diffraction
(c) Polarisation
(d) Refraction
Answer: a

A piece of wood is floating in water. If we heat the water, the piece of wood will:
(a) Increase in size
(b) Rise a little
(c) Sink a little
(d) Float at the same level
Answer: c

When cream is separated from milk
(a) The density of milk decreases
(b) The density of milk increases
(c) The density of milk remains unchanged
(d) None of these
Answer: b

colour of an opaque object is due to the colour it
(a) Reflects
(b) Absorbs
(c) Refracts
(d) Scatters
Answer: a

If a boy sitting in a railway train, moving at constant velocity, throws a ball straight up into the air.
(a) The ball will fall in front of him
(b) The ball will fall behind him
(c) The ball will fall into his hand
(d) The ball will not return downward
Answer: c

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