Potassium sulfide, also
known as dipotassium monosulfide, consists of two potassium ions bonded to a
sulfide atom, rendering the chemical formula K2S.<span>Rarely
found in nature due to its high reactivity with water, potassium sulfide is
refined from the more common potassium sulfate (K2SO4) and is used in many
industries</span>
Answer: Energy of reactants = 30, Energy of products = 10
Exothermic
Activation energy for forward reaction is 10.
Explanation:
Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and 
for the reaction comes out to be negative.
Energy of reactants = 30
Energy of products = 10
Thus as energy of the product < energy of the reactant, the reaction is exothermic.
Activation energy 
is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.
for forward reaction is (40-30) = 10.
The answer is: supersaturated solution.
A supersaturated solution contains more of the dissolved substance than could be dissolved by the solvent under normal circumstances.
A way to dissolve more sugar into a solution is heating a solution.
The more heat is added to a system, the more soluble a substance (in this example sugar) becomes.
The solution will become supersaturated if this solution is suddenly cooled at a rate faster than the rate of precipitation.
I'd say b, but i'm not 100 percent sure.<span />
