Why does carbon form covalent bonds?

Chlorophyll a had the molecular formula c55h72mgn4o5 how many atoms are in this molecule

Why are very high temperatures and pressures required for fusion to occur? to generate the neutrons that are needed to break the nuclei o to overcome the repulsion between the protons in the nuclei that join to maintain the proper conditions to keep the chain reaction going to keep the uranium fuel separate from the control rods

How many pm are there in 3.03 x 10^-14 miles?