Hierachy is a series of ordered groupings
Its either dead material or organisms that eat producers
The correct answer is Mitosis !! B !!
Mitosis did not do DNA varriations !!
Answer:
hydrogen gas dominated earth's first atmosphere?
Bones are made up of Calcium Phosphate given by the chemical formula,
. When bones are kept in Hydrochloric acid, given by the chemical formula, HCl, they become soft because the calcium compound present in the bones changes its form. The following double displacement reaction takes place when the bones are kept in HCl,
---> 
Calcium chloride is water soluble, and gets washed away. This makes the bone thin and soft.