Arrange the phases in the life cycle of the sun in order from the birth of the sun to the time in the far distant future when the sun has cooled.

The following signifies the life cycle of the Sun:  

a. Cast off the matter as planetary nebula.  

b. The process of nuclear fusion starts at its core.  

c. It appears in the form of a yellow star, as observed in the present time.  

d. After that, it moves into a red giant star stage.  

e. Converts into a white dwarf.  

f. Turns into a black dwarf.  

The Sun has initiated its life like any other kind of star, that is, from the gas and dust in a twirling cloud. The particles come close to each other and get condensed, unless and until there is sufficient pressure for the beginning of the nuclear fusion.  

The Sun is in the middle of its lifespan and is presently in the prime sequence phase. At this phase, in its life the Sun combines hydrogen and helium. It is estimated that about 50 percent of the core hydrogen has been used so far.  

well we can't tell you because we cant see the time give a screen shot or something.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.