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In the world of stars - class-VII

Description: in the world of stars
Number of Questions: 18
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Tags: our universe sky vision in the world of stars earth and beyond physics life cycle of stars
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What type of star is our Sun? 

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. low-mass star

  2. intermediate-mass star

  3. high-mass star

  4. blackhole

Show answer
Correct Option: A
Explanation:

Stars are sequence can range from a tenth of the mass of the sun to up to $200$ times as massive.

Sun is a low mass star.

What do astronomers mean when they say that we are all "star stuff"? 

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. that life would be impossible without energy from the Sun

  2. that life would be possible without energy from the Sun

  3. that the carbon, oxygen, and many elements essential to life were created by nucleosynthesis in stellar cores

  4. None of these

Show answer
Correct Option: C

The brightness of a star which can be seen from earth is called

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. absolute magnitude

  2. apparent magnitude

  3. light year

  4. parallax

Show answer
Correct Option: B

What is the first stage of a stars life.

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. Nebula collapsing under itself

  2. Supernova of old star

  3. Planets collapsing

  4. Fusion of atoms

Show answer
Correct Option: A
Explanation:

A star is a luminous globe of gas producing its own heat and light by nuclear reactions (nuclear fusion). They are born from the nebula and consist mostly of hydrogen and helium gas. Surface temperatures range from 2000 C to above 30,000 C, and the corresponding colors from red to blue-white. 

All stars are born in what phase of their lifecycle?

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. Supernova

  2. Red giant

  3. main sequence

  4. stellar nebula

Show answer
Correct Option: D
Explanation:

Nebulae are the collection of massive clouds of dust, hydrogen and helium gas, and plasma. These form the origin of the birth of a star.

What happens during the Main Sequence phase of a star?

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. Hydrogen atoms are fused into helium atoms

  2. The star explodes and releases energy

  3. Helium atoms are fused into heavy elements

  4. The star is born out of dust and gas

Show answer
Correct Option: A
Explanation:

Main sequence stars fuse hydrogen atoms to form helium atoms in their cores. About 90 percent of the stars in the universe, including the sun, are main sequence stars. 

A main sequence star is 

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. A star that shines steadily due to nuclear fusion

  2. Several stars close together

  3. A star with planets orbiting it

  4. A Nebula that skips a protostar and is instantly turns into a star.

Show answer
Correct Option: A

What is a Star?

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. A cloud of particles held together loosely by their own collective gravity

  2. A very big collection of matter, mostly gas compressed to incredible pressure and heat by gravity.

  3. A nuclear explosion caused by a growth of hydrogen onto the surface of a white dwarf star

  4. A ball of gas.

Show answer
Correct Option: B

What is the name of the process that forms heavy elements from atoms like helium?

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. Nuclear Fission

  2. Attraction

  3. Conjugation

  4. Nuclear Fusion

Show answer
Correct Option: A
Explanation:

Smaller elements fuse together to form massive elements. this process is known as nuclear fusion

A star in the main sequence will maintain a constant size

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. as long as its helium supply holds out.

  2. because its tendency to contract is opposed by the pressure of the hot interior.

  3. until it is devoured by black holes.

  4. provided that gravitational collapse does not overwhelm its photosphere.

Show answer
Correct Option: B
Explanation:

All main sequence stars (including the Sun) are in hydrostatic equilibrium. That is, the inward force of gravity, which tends to compress the star, is balanced by the outward force due to the pressure.

Stars are believed to originate

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. in clouds composed largely of hydrogen gas.

  2. when black holes eject excess matter and energy.

  3. when a supernova explode.

  4. when a cloud of helium starts to collapse and breaks into constituent protons (hydrogen atoms).

Show answer
Correct Option: A

A protostar is a developing star not yet hot enough to engage in the process of:

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. nuclear fusion

  2. nuclear fission

  3. atomic transmission

  4. atomic emission

Show answer
Correct Option: A
Explanation:

An object is considered a protostar for as long as material is still falling inward. For our Sun, and stars of the same mass, the protostar phase would have ended after approximately 100,000 years. After this, the protostar stops growing and the disk of material surrounding it is destroyed by radiation.


If the protostar was unsuccessful in acquiring enough mass, a brown dwarf will come into shape. These substellar objects that are unable to sustain hydrogen fusion reactions in their cores, due to their insufficient mass

The gaseous body that continues to form, now appears as a large red object called a:

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. protostar

  2. red dwarf

  3. red star port

  4. red giant

Show answer
Correct Option: A

What does the forming star become when the outward pressure equals the inward force of gravity?

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. stable main-sequence star

  2. unstable secondary white dwarf

  3. unstable main-sequence star

  4. stable secondary red giant

Show answer
Correct Option: A
Explanation:

Since the forces balance, it forms a stable main sequence star

When the core of a protostar reaches 10 million degrees Kelvin, the pressure is so great that the nuclear fusion of which gas begins?

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. hydroxide

  2. hydrogen

  3. heliogen

  4. hydrogate

Show answer
Correct Option: B
Explanation:

A star's composition is mostly made of gases of which hydrogen and helium forms the most largest component of it. Hydrogen being the lightest element will get fused to helium

After the initial contraction and when the temperature rises high enough, energy is radiated from the surface in the form of:

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. short-wavelength red light

  2. short-wavelength blue light

  3. long-wavelength red light

  4. long-wavelength orange light

Show answer
Correct Option: C

What is the range of star masses for high-mass stars? 

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. between 500 and about 1,000 solar masses

  2. between 200 and about 500 solar masses

  3. between 8 and about 100 solar masses

  4. between 2 and about 10 solar masses

Show answer
Correct Option: C
Explanation:

Range of star masses for high-mass stars varies from about $8$ to $200$ solar masses.

Answer is $C$.

The raw material for the formation of protostar is

physics in the world of stars evolution and end stages of stars life cycle of stars stars

  1. Coal

  2. Helium

  3. Hydrogen

  4. Uranium

Show answer
Correct Option: A
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