iGCSE Physics (0625) 6.2.2 Stars -Exam Style Questions Paper 2 - New Syllabus
▶️ Answer/Explanation
Detailed solution:
To convert a distance from meters to light-years, we use the defined value for one light-year: 1 ly=9.5×10 15 m.
The distance d in light-years is calculated by dividing the total distance in meters by the value of one light-year.
Distance in ly= 9.5×10 15 m/ly 6.6×10 20 m .
Performing the division: 9.5 6.6 ≈0.6947 and 10 15 10 20 =10 5 .
This results in 0.6947×10 5 , which simplifies in standard form to 6.9×10 4 light-years.
Therefore, Option B is the correct numerical value for this astronomical distance.
▶️ Answer/Explanation
Detailed solution:
A supernova occurs at the end of the life cycle of a high-mass star.
After a red supergiant exhausts its nuclear fuel, it collapses and explodes as a supernova.
This violent explosion leaves behind a dense remnant at the center.
Depending on the remaining mass, the remnant becomes either a neutron star or a black hole.
Options B and C are stages that occur before the explosion, while option D is the remnant of a low-mass star.
Thus, a neutron star is the only possible result of a supernova listed here.
▶️ Answer/Explanation
Detailed solution:
A supernova occurs at the end of the life cycle of a high-mass star after it has expanded into a red supergiant.
The violent explosion of the supernova disperses the outer layers of the star, creating a nebula containing hydrogen and new heavier elements.
Depending on the remaining mass of the core, the explosion leaves behind either a dense neutron star or a black hole at its center.
A white dwarf is formed from a less massive star via a planetary nebula, not a supernova.
Therefore, the two products formed directly from the explosion are a nebula and a neutron star.
This sequence aligns with the stellar evolution pathway for massive stars where $M > 8$ solar masses.