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.
It doesn't show the choices but, Biostimulation<span> involves the modification of the environment to stimulate existing bacteria capable of bioremediation. </span>
Volcanologists can predict eruptions—if they have a thorough understanding of a volcano's eruptive history, if they can install the proper instrumentation on a volcano well in advance of an eruption, and if they can continuously monitor and adequately interpret data coming from that equipment.
Anything containing <span> electricity </span> or magnetism. For example would be drinking water because that is the result of the electromagnetic force holding those hydrogen and oxygen atoms together.
Lights in a big city or even a small town create light pollution, which makes it really hard to see the stars at night. If you put a telescope on a mountain far away, there would be a lot less light pollution. The sky would be much clearer and you could see many more stars
