Evidence indicates that 251 million years ago a mass extinction of many life-forms occurred on earth. which form of life became extinct at this time?

The answer is trilobites. They are among the life forms that became extinct 250 million years after a calamity in the  Permian-Triassic extinction event. It is presumed that nearly 95% of world species were wiped from the face of the earth and this gave rise to the reign of the dinosaurs (that also became extinct 65 million years ago due to asteroid strike). The cause of this major extinction event is yet to be established.

the overall balanced equation

6co2 + 6h2o > c6h12o6 + 6o2

sunlight energy

where: co2 = carbon dioxide

h2o = water

light energy is required

c6h12o6 = glucose

o2 = oxygen

blue stars have the highest surface temp

stellar distances are usually expressed in light-years

the measure of a star's brightness is called magnitude

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