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.
Photosynthesis uses carbon and h20 as the reactants
Answer:
Chemical weathering
Explanation:
Chemical weathering is the process when rain chemicals react with rocks and minerals. In this process, the rocks are weakened. This chemical happening provokes the chemical reaction in the rock or in the mineral.
Chemical weathering is a spontaneous process and it leads to a more stable state for natural materials under a given set of conditions.
The force pushing against an area or surface
Answer:
D. DDT
Explanation:
DDT is highly persistent in the environment means that it break down very slowly in the environment. The half-life for DDT is from 2 to 15 years. Half-life is the time needed for the degradation of half of the compound. Persistent bio-accumulative toxic substances (PBTs) are chemicals that break down slowly in the environment and its accumulation in living organisms are toxic. Some PBTs are dispersed through air currents while some uses other environmental pathways, resulting in contamination of regions far from their points of origin.
