In the context of Schwarzschild black holes, the _____ is the boundary between the isolated volume ...

In the context of Schwarzschild black holes, the _____ is the boundary between the isolated volume of space-time and the rest of the Universe.
 
  A) bridge fragment
  B) event horizon
  C) pulsating point
  D) status curve

Question 2

In the context of the evidence on evolution of stars, you can estimate the _____ of a star cluster by observing the distribution of the points that represent its stars in the Hertzsprung-Russell (H-R) diagram.
 
  A) age
  B) density
  C) composition
  D) mass

Question 3

_____ was a type II supernova that was produced by the explosion of a hot, blue supergiant.
 
  A) SN 1572
  B) SN 1604
  C) SN 1987A
  D) SNR 1868

Question 4

Which of the following statements is true of stars?
 
  A) They die when they exhaust their fuel, allowing gravity to take control.
  B) The energy generated through nuclear fusion keeps their interiors cool.
  C) They avoid collapsing by balancing gravity through low pressures.
  D) The generation of energy from nuclear fusion prevents stars from resisting their own gravity.