Nitrogen is crucial to the marine life and it is disappearing because it cannot be assimilated by most organisms in the water.
Answer: 
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
Thus in the reactants, there are 2 atoms of hydrogen and 2 atoms of iodine .Thus there has to be 2 atoms of hydrogen and 2 atoms of iodine in the product as well. Thus a coefficient of 2 is placed in front of HI.
The balanced chemical reaction is:

I believe the answer is C) there is an obvious reasoning for this all you have to do is eliminate answers that don't seem right for example, A)the plates are all moving the same direction every plate moves in different directions. B) The plates are all the same size. Well, it's really obvious that that is not true because every plate has its different shape and size. D) where two plates meet, they always move apart. If this were true, then we would never have earthquakes when plates meet earthquakes happen. so there for the answer is C)
An ionic compound is a substance that contains atoms that are bonded together through an ionic bond, where electrons are transferred from one atom to another. For the given experiment above, the material that is missing from the list is WATER or solvent. It is necessary because conduction through water will help you identify if a sample compound is ionic through its electrolytes. <span>Ionic compounds that are soluble are typically electrolytes</span>