# UPSC

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

## History

General Science

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Q 1. Light year is

A

light emitted by the sun in one year.

B

time taken by light to travel from sun to earth.

the distance travelled by light in free space in one year.

D

time taken by earth to go once around the sun.

##### Explanation

1 light year = speed of light in vacuum
x no. of seconds in one year = (3 x 108) m/s x (365 x 24 x 60 x 60) s = 9.467 x 1015 m

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Q 2. Pitch is the effect produced in the ear due to the sound of some particular frequency.
1. Pitch of sound increases with the decrease in thickness of vibrating wires.
2. It does not depend upon the frequency of a vibrating body.
3. Lower frequency produces shrill sound. Which of the following is/are correct?

1 only

B

2 only

C

1 and 2

D

1, 2 and 3

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Q 3. Under which of the following conditions a concave mirror can form an image larger than the actual object?

A

When the object is kept at a distance equal to its radius of curvature.

B

When object is kept at a distance less than its focal length.

When object is placed between the focus and centre of curvature.

D

When object is kept at a distance greater than its radius of curvature.

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Q 4. Consider the following statements:
1. Light of longer wavelength are scattered much more than the light of shorter wavelength.
2. The speed of visible light in water is 0.95 times the speed in vacuum.
3. Radio waves are produced by rapidly oscillating electrical currents.
4. To detect the over speeding vehicles, police use the Doppler effect of reflected short radio waves.
Which of these statements are correct?

A

1 and 2

B

1 and 3

C

2 and 4

3 and 4

##### Explanation

Radio waves are a form of electromagnetic radiation, created whenever a charged object (in normal radio transmission, an electron) accelerates with a frequency that lies in the radio frequency (RF) portion of the electromagnetic spectrum. Thus statement 3 is correct. The Doppler's Effect shows a change in a wave's frequency received when it is either reflected from a moving object or generated on a moving object. Police radar speed detectors bounce a radio frequency wave off cars and use their internal electronics to determine the speed at which the object is moving by that frequency change. Therefore, statement 4 is also correct.

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Q 5. Consider the following statements:
1. A geo-stationary satellite is at an approximate height of 10,000 km.
2. FM transmission of music is of very good quality because the atmospheric or man made noises which are generally frequency variations can do little harm.
Which of the statement(s) given above is/are correct?

A

1 only

2 only

C

1 and 2 both

D

None

##### Explanation

The geostationary satellite is a satellite having a timeperiod of 24 hours. Using this time-period, the height of the satellite comes out to be approximately 35,800 km. FM broadcasting is a broadcast technology pioneered by Edwin Howard Armstrong that uses frequency modulation (FM) to provide high-fidelity sound over broadcast radio. FM transmission is quite immune to noise as compared to AM transmission. Noise is a form of amplitude variations in the transmitted signal due to atmosphere, industries, etc.

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Q 6. Consider the following statements :
1. A magnesium ribbon burns with a dazzling flame in air (oxygen) and changes into a white substance, magnesium oxide.
2. The reaction between nitrogen and hydrogen to give ammonia is an example of a combination reaction.
3. Action of heat on ferrous sulphate is an example of decomposition reaction.
Which of these statement(s) above is/are correct ?

A

1 and 2

B

1 and 3

C

2 and 3

1, 2 and 3

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Q 7. Consider the following statements:
1. Fluorine has the highest electron affinity in the periodic table.
2. Noble gases are placed extremely left in periodic table.
3. Magnesium is more metallic in nature than sodium. Which of these statement(s) is/are correct ?

A

1 and 2

B

1 and 3

1 only

D

2 only

##### Explanation

Noble gases are placed extremely right in periodic table. Sodium is more metallic than magnesium as it is more electropositive and has low ionisation energy.

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Q 8. Which of the following acts as an insulator against heat, cold and as a shock-absorber in the body ?

A

Dermis

B

Epidermis

Subcutaneous fat layer

D

None

##### Explanation

PV = K

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Q 9. Which of the following statements are true about brain?
1. The main thinking part of brain is hind brain.
2. Centres of hearing, smell, memory, sight etc. are located in fore brain.
3. Involuntary actions like salivation, vomiting, blood pressure are controlled by the medulla in the hind brain.
4. Cerebellum does not control posture and balance of the body.
Choose the correct option :

A

1 and 2

B

2 and 4

2 and 3

D

1, 2, and 3