What are some interesting facts about magnesium, lead, phosphorus and magnesium nitrate?

Lead can be extremely poisonous and was once used in many many paints but caused several deaths from lead poisoning so that was a biggie...
At the center of every chlorophyll molecule, in every plant, there is a magnesium ion. Magnesium is one of the two dozen or so elements that are required for life. 

 (C) Mass of KCl(s), mass of H20, initial temperature of the water, and final temperature of the solution

Explanation:

molar enthalpy of solution of KCl(s) is heat evolved or absorbed when one mole of KCl is dissolved in water to make pure solution . The heat evolved or absorbed can be calculated by the following relation.

Q = msΔt where m is mass of solution or water , s is specific heat and Δt is change in temperature of water .

So data required is mass of water or solution , initial and final temperature of solution , specific heat of water is known .

Now to know molar heat , we require mass of solute or KCl dissolved to know heat heat absorbed or evolved by dissolution of one mole of solute .