An astronomer examining a compact object could conclude that it was a black hole if it _____.
a. emits regular pulses of radiation
b. has a defined event horizon that emits X-rays
c. has an accretion disk
d. has a mass greater than 1.4 solar masses
e. has a mass greater than 3 solar masses
Question 2
Which statement best describes a theory?
a. A group of ideas about how something should be done, made, or thought about
b. A specific statement about nature that needs further testing
c. An idea considered so obviously true that the idea does not need to be questioned
d. A fundamental principle in which scientists have great confidence
e. A general description of some aspect of nature that has been thoroughly tested and widely accepted
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