Author Question: Which statement about black holes is true? A) Their event horizon is a physical surface boundary. ... (Read 20 times)

HCHenry · **on:** Jul 27, 2018

Which statement about black holes is true?

A) Their event horizon is a physical surface boundary.
B) Their main-sequence mass was 5-10 solar masses.
C) They form from 1.4 solar mass stars.
D) Their escape velocity is greater than the speed of light.
E) They form an event horizon at twice the Schwartzschild radius.

Question 2

Which of the following statements comparing halo stars to our Sun is not true?

A) Most stars in the halo have either died or are in their final stages of life, while the Sun is only in about the middle of its lifetime.
B) Most stars in the halo are less luminous than the Sun.
C) Most stars in the halo have cooler surface temperatures than the Sun.
D) Most stars in the halo contain a much lower percentage of heavy elements than the Sun.