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 :)
Cross over? i have no idea lol
Nitrogen is special because it is necessary for growth and reproduction. It's needed for plants and animals to survive. The main function for the atmosphere i believe is to give oxygen and nitrogen.
Answer: Auxins promote cell elongation and cell division in stems.
Answer:
The formula for density is the mass of an object divided by its volume. In equation form, that's d = m/v , where d is the density, m is the mass and v is the volume of the object. The standard units are kg/m³.