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Practice MCQ Questions and answers on Physics-GK

Learn and practice General Knowledge questions and answers on Physics with very easy and understandable explanations. GK questions are very helpful different type of competitive exams. Page-5 section-10

Each section contains 100 MCQs on Physics .
41
Which planet has the lowest density?
Discuss
Answer & Solution
Answer: Option C
Solution:
Saturn is mainly composed of the lightest two gases known, hydrogen and helium. It is the only planet in our solar system whose density is less than water.
42
The sensation of weightlessness in a spacecraft in an orbit is due to the
Discuss
Answer & Solution
Answer: Option B
Solution:
The sensation of weightlessness in a spacecraft in an orbit is due to the acceleration in the orbit which is equal to the acceleration due to gravity outside.
43
The different colours of different stars are due to the variation of
Discuss
Answer & Solution
Answer: Option A
Solution:
The colour of a star – which varies from bluish-white and yellow to orange and red – is primarily due to its composition and effective temperature. And at all times, stars emit light which is a combination of several different wavelengths. On top of that, the colour of a star can change over time.
44
Which of the following is correct about the properties of Gravitational Forces?
Discuss
Answer & Solution
Answer: Option B
Solution:
It is a universal attractive force. It is directly proportional to the product of the masses of the two bodies. It obeys inverse square law. It is a long range force and does not need any intervening medium for its operation.
45
In the absence of the earth's atmosphere, sky would appear
Discuss
Answer & Solution
Answer: Option D
Solution:
Without an atmosphere the sky appears black, as evidenced by the lunar sky in pictures taken from the moon. But even a black sky has some lightness. At night, the sky always has a faint color, called "skyglow" by astronomers.
46
We always see the same face of the moon, because
Discuss
Answer & Solution
Answer: Option C
Solution:
The Moon does not rotate. The Moon does spin on its axis, completing a rotation once every 27.3 days; the confusion is caused because it also takes the same period to orbit the Earth, so that it keeps the same side facing us.
47
The fact that the planets move around the Sun, not in circles but in ellipses, was first demonstrated by
Discuss
Answer & Solution
Answer: Option C
Solution:
The fact that the planets move around the Sun, not in circles but in ellipses, was first demonstrated by Johannes Kepler.
48
A bomb explodes on the moon. You will hear its sound on earth after ________
Discuss
Answer & Solution
Answer: Option D
Solution:
As sound is produced due to vibrations in the medium particle, that is, it needs some medium for propagation and moon does not have any atmosphere. So ultimately, no medium for propagation of waves or vibrations of a medium particle.
49
Stars are held together by
Discuss
Answer & Solution
Answer: Option A
Solution:
A star is a sphere of gas held together by its own gravity. The closest star to Earth is our very own Sun, so we have an example nearby that astronomers can study in detail.
50
The minimum number of geostationary satellites needed for uninterrupted global coverage is :
Discuss
Answer & Solution
Answer: Option A
Solution:
In theory, 2 satellites in diametrically opposite geosynchronous orbits could cover the planet. In order for the satellites to communicate, a minimum of 3 would be needed, each at a 60 degree angle to the others. At this point, the strength and quality of coverage increases proportionally to the number of satellites.