As you did not state what the question is you just wrote a statement, I am guessing this is a True or False question. If there is more to the question please comment and Id be happy to help you answer more but if this is T/F then Ill answer it here right now.
A main-sequence star maintains a stable size as long as there is enough hydrogen to fuse into helium. True or False?
Answer: True
Hope this Helps, good luck, and comment if you need help on anything else :)
a chemical element or substance required in trace amounts for the normal growth and development of living organisms.
The range of temperatures in which an insect is able to live and reproduce is one element of that organism's niche, a description of its ecological requirements.