# Model Practice Test- 3

## 25 Questions MCQ Test Science & Technology for UPSC CSE | Model Practice Test- 3

Description
Attempt Model Practice Test- 3 | 25 questions in 30 minutes | Mock test for UPSC preparation | Free important questions MCQ to study Science & Technology for UPSC CSE for UPSC Exam | Download free PDF with solutions
QUESTION: 1

Solution:
QUESTION: 2

### Non-stick frying pans are coated black with teflon, a material that is resistant to heat. Teflon is a polymer of:

Solution:

D is the correct option.Polymerization of tetrafluoroethylene produces polytetrafluoroethylene (PTFE) polymers such as Teflon and Fluon. PTFE is one of the two fluorocarbon resins composed wholly of fluorine and carbon.

QUESTION: 3

### Food articles like milk, vegetables and bread are kept in a refrigerator. Medicines are labelled ‘Store in a cool, dry place’. By keeping at low temperatures, they are prevented from decay or destruction, because:

Solution:
QUESTION: 4

Bell- metal is t he metal u sed for m aking bell s for churches. This metal gives the bell its special, ringing sound. It contains:

Solution:
QUESTION: 5

Ice floats on water because it has an open structure compared to water and therefore occupies a greater volume of space for the same weight. This open structure of ice is due to:

Solution:

The correct option is B.
This unusual behavior has its origin in the structure of the water molecule. There is a strong tendency to form a network of hydrogen bonds, where each hydrogen atom is in a line between two oxygen atoms. ... It is this open solid structure that causes ice to be less dense than liquid water.

QUESTION: 6

Very fast conduction of electricity by matter is called supercon-ductivity. This happens when matter is:

Solution:

The correct option is B.
The resistance of a conductor is directly proportional to the temperature. So, when it is cooled below a certain temperature called critical temperature, the resistance tends to drop to zero and superconductivity can be observed.

QUESTION: 7

Many fruits have pleasant odour. Some of the pleasant odour of common fruits are due to:

Solution:

Esters occur widely in nature and generally have pleasant odors and are often responsible for the characteristic fragrances of fruits and flowers.

QUESTION: 8

Glycol is used in car radiators as

Solution:
QUESTION: 9

What are asteroids?

Solution:
QUESTION: 10

Which of the following statements in correct?

1. The earth spins at the rate of 1500 km per hour.
2. The earth spins faster during September than during March in any year.
3. The latitude 23.5° north of the earth’s equator is called the Tropic of Cancer.
4. The Tropic of Capricon is the latitude 23.5°south of the earth’s equator.
Solution:

i.The Earth spins around at over 1,500 km/hr - that's over 4 times faster than a Formula 1 car at top speed! The Earth rotates from west to east, which makes the Sun appear to rise in the east and set in the west, but it is due to the Earth spinning rather than the Sun moving.

ii.Earth’s axis is also inclined at approximately 23.439° towards the ecliptic. This means that when the Sun crosses the equator at both equinoxes, it’s daily shift relative to the background stars is at an angle to the equator. In June and December, when the Sun is farthest from the celestial equator, a given shift along the ecliptic corresponds to a large shift at the equator.

So apparent solar days are shorter in March and September than in June or December. In northern temperate latitudes, the Sun rises north of true east during the summer solstice, and sets north of true west, reversing in the winter. The Sun rises south of true east in the summer for the southern temperate zone, and sets south of true west.

iii.Located at approximately 23.5 degrees north latitude (i.e., 23.5 degrees north of the equator), the Tropic of Cancer is the line of latitude that's the northern boundary of the area referred to as the tropics.

iv.The Tropic of Capricorn is a parallel of latitude on the Earth, 23.5 degrees south of the equator. On the northern winter solstice/southern summer solstice (around the 22nd December each year), the Sun reaches its most southerly declination of -23.5 degrees.

QUESTION: 11

How many meteors fall through the earth’s atmosphere every day?

Solution:
QUESTION: 12

Which of the following statements is correct?

1. The Earth has 81 times the mass of the Moon.
2. Moon and the Earth are of the same age.
3. Mercury and Pluto have no atmosphere
4. Sun rotates faster in its equatorial region (once in 27 days) than in its polar region (once in 32 days).
Solution:
QUESTION: 13

The largest organ of the human body is

Solution:
QUESTION: 14

The wavelength of gamma rays is

Solution:
QUESTION: 15

Under sui table c onditi on s, four hydrogen nuc lei combine to form the nucleus of helium atom. This phenomenon is known as

Solution:
QUESTION: 16

Which of the following statements is correct?

1. X-ray is produced w hen cathode rays strike metals of high atomic weight.
2. The velocity of light in empty space will change if the source of light is set into motion.
3. Choke coil is used as a resistance in A.C. circuits.
4. Gamma rays can not be deflected by a magnetic field.
Solution:
QUESTION: 17

If the direction of current through a resistance i s reversed, then the heating effect will

Solution:

The correct answer is C as f the direction of current through a resistance i s reversed, then the heating effect will remain unchanged  so ,no effect.

QUESTION: 18

Which of the following statements is true?

1. In order to convert a galvanometer in to an ammeter, a small resistance must be connected in parallel with the galvanometer's coil.
2. If the diameter of a w ire is reduced to half its previous value, then its resistance will increase four times.
3. During charging of a lead accumulator, the density of sulphuric acid in the accumulator increases.
4. In the electrolysis of water oxygen is given off at the cathode.
Solution:
QUESTION: 19

In electrolysis of water, if 1 gm of hydrogen is liberated during a given time, then the amount of oxygen liberated during the same will be:

Solution:
QUESTION: 20

Which of the following statements is true?

1. Velocity of sound in air is proportional to the squareroot of its absolute temperature.
2. Under similar conditions the speed of sound in hydrogen is four times the speed in oxygen.
3. Only odd harmonics are present in the longitudinal vibrations in the air in a closed pipe.
4. Two identical waves are said to be coherent if their phases are equal.
Solution:
QUESTION: 21

If we look at a red flower through a green glass during the day, the flower will look

Solution:
QUESTION: 22

Which of the following statements is true?

1. Images formed by a concave lens are always smaller than the object.
2. The least distance of distinct vision for a normal eye is 25 cm.
3. A convex lens when immersed in water will have its focal length increased four times approximately.
Solution:
QUESTION: 23

23. At the temperature of boiling point of a liquid, its vapour pressure is

Solution:
QUESTION: 24

The density of mercury is

Solution:
QUESTION: 25

Which of the following contains photosynthetic pigment?

Solution:
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