# UPSC > General Science

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

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Q 1.

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Incorrect-0.667

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

Q 2.

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The gravitational force with which the earth attracts the moon

A

is equal to the force with which the moon attracts the earth.

B

is equal to the force with which the moon attracts the earth.

C

is greater than the force with which the moon attracts the earth.

varies with the phases of the moon.

Q 3.

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Mercury boils at 367°C. However, mercury thermometers are made such that they can measure temperature up to 500°C. This is done by

A

maintaining vacuum above mercury column in the stem of the thermometer.

filling nitrogen gas at high pressure above the mercury column.

C

filling nitrogen gas at low pressure above the mercury level.

D

filling oxygen gas at high pressure above the mercury column.

##### Explanation

By increasing pressure above mercury column, the boiling
point can be increased.

Q 4.

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From the following statements, concerning ideal gas at any given temperature T,
1. The coefficient of volume expansion at constant pressure is same for all ideal gases.
2. The average translational kinetic energy per molecule of oxygen gas is 3KT (K being Boltzmann constant).
3. In a gaseous mixture, the average translational kinetic energy of the molecules of each component is same.
4. The mean free path of molecules increases with the decrease in pressure.
Select the correct ones :

A

1 and 2

B

3 and 4

1, 3 and 4

D

1, 2 and 3

##### Explanation

Y v = Y p = 1 / K
vp273
3
E = RT is same for all ideal gases at same temperature. The
2
, kT
mean free path, ^ = 2 ; so it increases with decrease
H V2rcdin pressure.

Q 5.

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If you are at open-air concert and someone's head gets between you and the orchestra, you can still hear the orchestra because

A

sound waves pass easily through a head.

a head is not very large compared with the wavelength of the sound.

C

the sound is reflected from the head.

D

the wavelength of the sound is much smaller than the head.

Q 6.

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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

Q 7.

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A proton (mass m and charge + e) and an a-particle (mass 4m and charge + 2e) are projected with the same kinetic energy at right angles to the uniform magnetic field. Which one of the following statements will be true?

A

The a-particle will be bent in a circular path with a small radius than that for the proton.

B

The radius of the path of the a-particle will be greater than that of the proton.

The a-particle and the proton will be bent in a circular path with the same radius.

D

The a-particle and the proton will go through the field in a straight line.

##### Explanation

V2mK . 4m
r = i.e. r
qB q
Here kinetic energy K and B are same.
. rp qa = 2qp = j
" ra Pa'qp 4mp qp

Q 8.

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In domestic circuits, wires with red insulations are used as live wires, whereas.

A

the wires with black insulations are used as neutral (or negative) wires.

B

the wires with green insulations or steel wires are used as earth wires.

C

the wires with black insulations are used for positive terminals.

and (b) only

##### Explanation

Conventionally Wires with red insulations are conventionally used as live wires, whereas the wires with black insulations are used as neutral (or negative) wires and the wires with green insulations or steel wires are used as earth wires. However it is not a rule.

Q 9.

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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.

Q 10.

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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.

Q 11.

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Consider the following statements :
1. Collation is a process of sorting at receiving end .
2. Encoding of signal is required for modulation at transmitting end.
3. Long wave broadcast transmitter are used for temperate countries.
Which of the above statements are correct?

A

1 and 2

2 and 3

C

1 and 3

D

1, 2 and 3

##### Explanation

Collation is the process of collecting information from different sources and arranging in correct order.

Q 12.

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Incorrect-0.667

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.

Q 13.

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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

Q 14.

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Incorrect-0.667

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.

Q 15.

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Tyndall phenomena is not exhibited by
1. NaCl solution 2. starch solution
3. urea solution 4. FeCl3 solution

A

1, 2 and 3

1, 3 and 4

C

1, 2 and 4

D

2, 3 and 4

##### Explanation

Scattering of light (Tyndall effect) is exhibited by a colloidal solution. Among the given solutions starch solution is a colloid whereas other are example of true solution.

Q 16.

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Boyle's law states that the

A

pressure of a gas is directly proportional to the temperature at constant volume.

pressure of a gas is inversely proportional to the volume at constant temperature.

C

volume is directly proportional to the temperature at constant pressure.

D

None

##### Explanation

Boyle's law
P X
V
P = K
V

Q 17.

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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

Q 18.

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Incorrect-0.667

Which of the following statement(s) is/are true?
1. Synapsis of homologous chromosomes takes place during Prophase I of meiosis.
2. Division of centromeres takes place during Anaphase I of Meiosis.
3. Spindle fibres disappear completely in Telophase of Mitosis.
4. Nucleoli reappear at Telophase I of meiosis. Choose the correct option :

A

1 only

B

3 only

C

1 and 2

1, 3 and 4

##### Explanation

Division of centromeres takes place during anaphase II of meiosis.

Q 19.

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Which of the following statements are true / false ?
1. Trimerous condition of floral whorl is characteristic of dicotyledons.
2. Adiantum is also called walking fern.
3. In gymnosperms the vascular system consists of xylem without vessels and phloem with companion cells.
4. Riccia and Marchantia are liverworts. Choose the correct option :

A

1 and 2 are true and 3 and 4 are false

B

1 and 3 are true and 2 and 4 are false

C

1 and 4 are true and 2 and 3 are false

2 and 3 are true and 1 and 4 are false

##### Explanation

Trimerous floral whoal is not a characterstic feature of cigther dicots or monocots. Riccia and Marchantia are bryophytes.

Q 20.

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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