4.) an element cannot be decomposed by a chemical change, it is a pure substance and no other materials compose it.
That is false because aluminum melts at 2,470C
You can put a known amount sodium into some sort of time release mechanism such as a pill made from soluble material. Then you can place the sodium into a calorimeter with a known mass of water and record the temperature change the water undergoes during the reaction. Then you can use the equation q(water)=m(water)c(water)ΔT to find the amount of heat absorbed by the water. since the amount of heat absorbed by the water is the amount of heat released from the sodium, q(sodium)=-q(water). Than you can use the equation q(sodium)=m(sodium)c(sodium)ΔT and solve for c(sodium)
I hope this helps and feel free to ask about anything that was unclear in the comments.
Prarie Grass Protects soil ( And this is just what I think, so I am sorry if I am wrong)
But I think that the grass is there so that the dirt doesn't fly away.
Answer: The coefficient in front of AgCl when the equation is properly balanced is 2.
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.
Decomposition is a type of chemical reaction in which one reactant gives two or more than two products.
Decomposition of silver chloride is represented as:

Thus the coefficient in front of AgCl when the equation is properly balanced is 2.