# Astronut Of The Week -2

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Quizzes Created: 1 | Total Attempts: 96
Questions: 12 | Attempts: 96

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• 1.

### Which of the following is NOT a theory about the end of the universe?

• A.

Big Bang

• B.

Big Freeze

• C.

Big Bounce

• D.

Big Rip

A. Big Bang
Explanation
The Big Bang theory proposes that the universe originated from a singularity and has been expanding ever since. On the other hand, the Big Freeze theory suggests that the universe will continue to expand until all its energy is depleted, resulting in a cold and lifeless state. The Big Bounce theory posits that the universe undergoes cycles of expansion and contraction, while the Big Rip theory suggests that the expansion of the universe will continue to accelerate, eventually tearing apart all matter. Therefore, the correct answer is Big Bang, as it is a well-established theory explaining the beginning of the universe, rather than its end.

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• 2.

### The Schwarzchild radius of an object:

• A.

Depends solely on its mass

• B.

Depends solely on its density

• C.

Depends on both mass and density

• D.

Depends on its surface area

A. Depends solely on its mass
Explanation
The Schwarzschild radius of an object refers to the radius at which the object would need to be compressed in order to become a black hole. This radius is directly proportional to the mass of the object and is independent of its density or surface area. Therefore, the correct answer is that the Schwarzschild radius depends solely on the mass of the object.

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• 3.

### The LIGO-India project will be jointly coordinated and executed by which of the premier Indian institutions1) IUCAA2) Indian Institute of Astrophysics3) Institute for Plasma Research

• A.

1,2

• B.

2,3

• C.

1,3

• D.

All the above

C. 1,3
Explanation
The LIGO-India project will be jointly coordinated and executed by IUCAA (Inter-University Centre for Astronomy and Astrophysics) and Institute for Plasma Research. This means that both IUCAA and Institute for Plasma Research will work together to oversee and carry out the LIGO-India project. The Indian Institute of Astrophysics is not involved in this project. Therefore, the correct answer is 1,3.

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• 4.

### A star whose mass is 5 times larger than the Sun's and whose luminosity is 100 times larger than the Sun's has a main-sequence lifetime about

• A.

5 times longer than the Sun's

• B.

500 times longer than the Sun's

• C.

5 times shorter than the Sun's

• D.

20 times shorter than the Sun's

D. 20 times shorter than the Sun's
Explanation
A star with a mass 5 times larger than the Sun's and a luminosity 100 times larger than the Sun's is much more massive and brighter than the Sun. This means that it will burn through its nuclear fuel much faster than the Sun. The more massive a star is, the faster it burns through its fuel and the shorter its main-sequence lifetime. Therefore, the star's main-sequence lifetime will be 20 times shorter than the Sun's.

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• 5.

### Which of the following particle is responsible for carrying away the missing energy and momentum in a nuclear decay process.

• A.

Alpha particle

• B.

Neutrino

• C.

Lepton

• D.

Proton

B. Neutrino
Explanation
Neutrinos are particles that have very little mass and no electric charge. They are produced in various nuclear processes, including nuclear decay. In a nuclear decay process, such as beta decay, a neutron in the nucleus of an atom is transformed into a proton, and in the process, a high-energy electron (beta particle) and a neutrino are emitted. The neutrino carries away the missing energy and momentum from the decay, ensuring that energy and momentum are conserved. Therefore, the correct answer is neutrino.

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• 6.

### When an object crosses the event horizon and enters the black hole, for an external observer in an inertial reference frame

• A.

The object will disappear immediately

• B.

The object will first emit light then disappear after infinite time

• C.

The object will seem to stretch along the axis joining it and the observer

• D.

The object will stay at the event horizon and disappear after infinite time

D. The object will stay at the event horizon and disappear after infinite time
Explanation
When an object crosses the event horizon and enters a black hole, for an external observer in an inertial reference frame, the object will appear to stay at the event horizon and eventually disappear after an infinite amount of time. This is due to the extreme gravitational forces near the event horizon, causing time to slow down significantly. From the perspective of the external observer, the object's time appears to slow down, making it seem as if the object is frozen at the event horizon. However, as time progresses infinitely, the object will eventually disappear completely from view.

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• 7.

### The figure below illustrates the plausible shapes of the universe in accordance with general relativity. What does the symbol Ω0 indicate?

• A.

Actual or observed mass density

• B.

Critical mass density

• C.

Density parameter

• D.

Cosmological constant

C. Density parameter
Explanation
The symbol Ω0 indicates the density parameter. In the context of general relativity, it represents the ratio between the actual or observed mass density of the universe and the critical mass density. The critical mass density is the threshold value that determines whether the universe will expand forever or eventually collapse. Therefore, the density parameter provides important information about the overall density of the universe and its potential fate.

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• 8.

### If the energy of the universe is _______, it will eventually collapse into a Big Crunch.

• A.

Positive

• B.

Zero

• C.

Negative

• D.

None

C. Negative
Explanation
If the energy of the universe is negative, it will eventually collapse into a Big Crunch. This is because negative energy has a gravitational effect that opposes the expansion of the universe. As a result, the gravitational pull of negative energy would eventually overcome the expansion and cause the universe to collapse in on itself. This is in contrast to positive or zero energy, which would not have the necessary gravitational effect to cause a Big Crunch.

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• 9.

### Our universe is dominated by…

• A.

Ordinary matter

• B.

Dark matter

• C.

Dark energy

• D.

Equal of all

C. Dark energy
Explanation
Dark energy is the correct answer because it is believed to be the dominant component of the universe, accounting for approximately 68% of its total energy. Dark energy is a hypothetical form of energy that is thought to be responsible for the accelerating expansion of the universe. Unlike ordinary matter and dark matter, which have gravitational effects that can be observed, dark energy's nature and properties are not well understood. However, its presence is inferred from the observed behavior of distant galaxies and the cosmic microwave background radiation.

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• 10.

### The Crab Nebula (M1) is a

• A.

. planetary nebula

• B.

Supernova remnant

• C.

Cluster associated with nebulosity

• D.

Pulsar

B. Supernova remnant
Explanation
The Crab Nebula, also known as M1, is a supernova remnant. This means that it is the remains of a massive star that exploded in a supernova event. The explosion scattered the outer layers of the star into space, creating a nebula of gas and dust. The Crab Nebula is one of the most studied objects in astronomy and is located in the constellation Taurus. Its remnant is still expanding, and it is also home to a pulsar, which is a highly magnetized, rotating neutron star.

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• 11.

### There are two types of black holes__________ and _____________

• A.

Gravitational and Supermassive

• B.

Stellar and Supermassive

• C.

Quasars and Dwarfs

• D.

Stellar and Gravitational

B. Stellar and Supermassive
Explanation
The correct answer is "Stellar and Supermassive." Black holes are categorized into two main types based on their size. Stellar black holes are formed from the collapse of massive stars, while supermassive black holes are found at the centers of galaxies and are millions or billions of times more massive than the Sun.

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• 12.

### The _____________ is speculated to be about 1 light year from the sun

• A.

Kuiper Belt

• B.

Van Allen Belt

• C.

Oort Cloud

• D.

Asteroid Belt

C. Oort Cloud
Explanation
The Oort Cloud is a hypothetical region of space located about 1 light year from the sun. It is believed to be a vast, spherical shell of icy objects that surrounds the solar system. The Oort Cloud is thought to be the source of long-period comets, which occasionally enter the inner solar system. Although it has never been directly observed, its existence is inferred from the orbits of comets and other evidence. The other options listed, such as the Kuiper Belt, Van Allen Belt, and Asteroid Belt, are all different regions or structures within the solar system and are not speculated to be about 1 light year from the sun.

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