The Universe (Part-2)

Total Questions: 50

21. Which one of the following is known as 'Morning Star'? [U.P. Lower Sub. (Pre) 2015]

Correct Answer: (b) Venus
Solution:Venus is called as 'Morning Star' and 'Evening Star as it is the brightest planet of all. Venus is also called 'twin sister' of earth as venus and earth are almost the same size and same mass and have a very similar composition.

22. Consider the following statements: [I.A.S. (Pre) 2005]

Assertion (A): Existence of human life on Venus is highly improbable.

Reason (R) : Venus has an extremely high level of carbon dioxide in its atmosphere.

Code:

Correct Answer: (a) Both A and R are true, and R is the correct explanation of A
Solution:There is evidence of the atmosphere at Venus. The atmosphere of Venus mainly contains Carbon dioxide (CO₂) 96.5%. In addition to this, the surface temperature of Venus is more than 400° C.

Hence due to the above reasons (CO₂) and high temperature, the possibility of life on Venus is highly unlikely, Hence, both Assertion (A) and Reason (R) are correct and (R) is the correct explanation of Assertion (A).

23. The planet which is called twin sister of the earth is - [U.P. Lower Sub. (Pre) 2008, U.P.P.C.S. (Pre) 2007]

Correct Answer: (b) Venus
Solution:Venus is called sister planet or twin planet of Earth. Venus is also known as the brightest planet, the Morning Star and the Evening Star etc.

It is the second planet from the Sun and the sixth largest planet. It is the hottest planet in the Solar System, even though Mercury is twice as close to the Sun and receives four times more solar energy.

Venus' atmosphere traps heat from the sun as an extreme version of the greenhouse effect that warms Earth. Temperatures on Venus reach 880 degrees Fahrenheit (471 degrees Celsius), which is more than hot enough to melt lead. Venus and Earth are often called twins because they are similar in size, mass, density, composition, and gravity.

Venus is only a little bit smaller than Earth, with amass of about 80% of Earth's. It is not a gas planet, but a rocky planet. The interior of Venus is made up of a central iron core and a rocky mantle, similar in composition to Earth.

Its atmosphere is made up of mainly carbon dioxide (96%) and nitrogen (3.5%), with trace amounts of carbon monoxide, sulfur dioxide, water vapour, argon, and helium making up the other 0.5%.

24. The Spacecraft "Magellan" was sent to - [U.P.P.C.S. (Pre) 1991]

Correct Answer: (d) Venus
Solution:The Magellan spacecraft was sent to Venus on a surface Mapping mission. The spacecraft was launched on 04 May 1989, which arrived at Venus orbit on 10 August, 1990. It was named after Potuguese explorer of the sixteenth century, Ferdinand Magellan.

25. Who amongst the following was the first to state that the Earth was spherical? [I.A.S. (Pre) 2001]

Correct Answer: (a) Aristotle
Solution:Aristotle (384-322 BC) was a Greek philosopher and Polymath. In chapter-14, Volume-2 of his book "On the Heavens" he described Earth as a spherical body. This book was translated into English by J. L. Stocks.

The Geographer and Philosopher Ptolemy (second century A.D.) Strabo (First century BC-First Century AD.) and Copernicus (15th-16th century A.D.) was the Geographer/Philosopher after Aristotle. Thus Aristotle was the first philosopher who argued that the Earth is spherical in shape.

26. In the form of the organism, the Scientific name of Earth is- [U.P.P.C.S. (Pre) 1999]

Correct Answer: (c) Green Planet
Solution:The life on the Earth is possible due to the ecology present on it. Earth is known as Green Planet for the presence of ecology. Earth is made up of several layers.

According to the mechanical properties, Earth's layers are the Lithosphere, Asthenosphere, Lower mantle (also known as mesospheric mantle), Outer core, and Inner core. Chemically, the layers are the Crust, Mantle, and Core.

The crust is the uppermost layer of the Earth. It possesses just 1% of Earth's mass but contains almost all known life in the universe. The crust, created by the dynamic geologic forces, continues to be shaped by the planet's movement and energy.

Plate tectonics is responsible for the formation and destruction of crustal materials. The Earth's Mantle is divided into mainly two layersi.e., the Upper mantle and the Lower mantle. The discontinuity between the upper mantle and the lower mantle is known as Repetti Discontinuity.

The extremely hot and dense center of our planet is known as the Earth's core. The Gutenberg discontinuity signals the end of the mantle and the commencement of Earth's liquid outer core.

27. The diameter of the Earth is - [Uttarakhand P.C.S. (Mains) 2006]

Correct Answer: (c) 12,800 km
Solution:The equatorial diameter of the Earth is 12,756 km (Near about 12800 km.) and the polar diameter is 12,714 km.

Earth is made up of several layers. According to the mechanical properties, Earth's layers are the Lithosphere, Asthenosphere, Lower mantle (also known as mesospheric mantle), Outer core, and Inner core. Chemically, the layers are the Crust, Mantle, and Core.

The crust is the uppermost layer of the Earth. It possesses just 1% of Earth's mass but contains almost all known life in the universe. The crust, created by the dynamic geologic forces, continues to be shaped by the planet's movement and energy.

Plate tectonics is responsible for the formation and destruction of crustal materials. The Earth's Mantle is divided into mainly two layersi.e., the Upper mantle and the Lower mantle. The discontinuity between the upper mantle and the lower mantle is known as Repetti Discontinuity.

The extremely hot and dense center of our planet is known as the Earth's core. The Gutenberg discontinuity signals the end of the mantle and the commencement of Earth's liquid outer core.

28. Consider the following statements and select the correct answer from the codes given below: [I.A.S. (Pre) 2003]

Statement (A): Moving from one place on earth to another place of high latitude, the weight of an object decreases.

Reason (R) : Earth is not a perfect sphere.

Choose the correct answer by using code given below -

Correct Answer: (d) (A) is false, but (R) is true.
Solution:The centrifugal force generated by the Earth's axis rotation is maximum at equator. As the result of this force, the weight of any object is minimum at Equator and maximum at poles and also increases towards high latitude, Thus, statement (A) is false.

The shape of Earth is nearest to an oblate spheroid. Earth is pudgier at the equator than at Poles due to earth rotation. Earth is not perfectly spherical in shape and this shape known as Geoid. Thus, Reason (R) is true.

29. Time taken by light emitted from sun to reach earth is- [U.P.P.C.S. (Mains) 2005, M.P.P.C.S. (Pre) 1996, 38th B.P.S.C. (Pre) 1992]

Correct Answer: (c) 8 minutes
Solution:The radiation from the sun which is popularly known as sunlight is a mixture of electromagnetic waves. Sunlight takes an average of 8 minutes and 19 seconds to travel from the Sun to the Earth.

These electromagenetic energy waves travel with a speed of 3.0×1018 m./sec. Thus, the closest answer given in option (c) is true.

30. The sunlight from the sun to the earth reaches in : [65th B.P.S.C. (Pre) 2019]

Correct Answer: (c) 8 minutes
Solution:Light travels at a speed of 3.0×1018 m./sec. It takes 499.0 sec. (approx. 8 min 19 sec.) for light to travel from the sun to the Earth. The average distance between the Sun and Earth is about 150 million kilometers (93 million miles). Light travels at a speed of approximately 299,792 kilometers per second (186,287 miles per second).

To calculate the time it takes for light to travel this distance, you divide the distance by the speed of light: 150,000,000 km / 299,792 km/s = 499 seconds. 499 seconds is roughly equal to 8 minutes and 19 seconds. This means that when we see the Sun, we are seeing it as it was 8 minutes and 19 seconds ago