Anail rusts when the iron in the nail reacts very slowly with oxygen to form a new substance and heat. this is an example of a(n) reaction. a. fusion b. fission c. exothermic d. endothermic

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.

answer: b

coz red blood cells marrow and circulates the body for 120 days.

the answer u all are looking for is 4000000000000000000000 million years.