10 questions ยท Form 2 Science Bab 10: Stars and Galaxies in the Universe
Which physical process powers a main sequence star and generates light and heat energy?
Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.
1. Which physical process powers a main sequence star and generates light and heat energy?
Answer: B
In a star's core, extreme temperature and gravitational pressure fuse hydrogen nuclei into helium through nuclear fusion, releasing immense energy.
2. Which star color indicates the HOTTEST surface temperature?
Answer: D
Blue stars have the highest surface temperatures (ranging from 25,000 K to over 50,000 K), whereas red stars are the coolest.
3. What catastrophic cosmic explosion occurs when a supermassive star dies?
Answer: B
When a massive or supermassive star exhausts its nuclear fuel, its core collapses rapidly, causing a violent supernova explosion.
4. On which specific outer arm of the Milky Way galaxy is our Solar System located?
Answer: C
Our Solar System resides on a minor spiral arm of the Milky Way called the Orion Arm (or Orion Spur).
5. What will be the final remnants of a medium-sized star like our Sun at the end of its life cycle?
Answer: C
After expanding into a Red Giant and casting off its outer layers as a planetary nebula, a medium-mass star cools down to become a White Dwarf.
6. What unit of distance is defined as the distance traveled by light through a vacuum in one earth year?
Answer: B
A light-year (ly) is a unit of astronomical distance equal to the distance light travels in one year (approx. 9.5 trillion km).
7. Why does a star stop shining at the end of its White Dwarf stage?
Answer: B
A white dwarf no longer undergoes nuclear fusion; it slowly radiates its remaining heat into space until it completely cools.
8. Which remnant is formed from the core collapse of the MOST massive supermassive stars following a supernova?
Answer: C
If the collapsing core of a dead star exceeds approximately 3 solar masses, gravity is so intense that it forms a black hole from which even light cannot escape.
9. What force pulls cosmic hydrogen gas and dust together inside a nebula to initiate star formation?
Answer: C
Gravitational attraction slowly pulls gas and dust particles toward a central point inside a nebula, increasing density and pressure until nuclear fusion ignites.
10. In what chronological order does a medium-mass star evolve throughout its life?
Answer: A
Stars form in a Nebula, enter the Main Sequence stage, expand into a Red Giant, and eventually shrink into a White Dwarf.