Answer: 
Explanation: A double displacement reaction is one in which exchange of ions take place.
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.

Answer: (i) F = 2
(ii) F = 3
(iii) F = 2
Explanation:
We would be applying the famous Gibbs Phase Rule to explaining this problem;
By applying the formula;
F+P = C +2
Where P = this represent the phase
F = this is called the degree of freedom
C = this represent the component in the system
Ok let us begin;
(i). from this we can see that there are 2 components i.e. (water + ethanol) and the phase in question is a vapor phase + liquid phase.
So from the formula;
F = C-P+2
F = 2 – 2 + 2 = 2
Therefore, F = 2.
(ii). Also, from the statement, we can figure there are 3 components, while the phases are two like the previous one above, i.e. liquid + vapor
F = 3 – 2 + 2 = 5 – 2 = 3
F = 3
(iii). From this statement, we can figure there are 3 components, and the phases are 3 i.e. (2 liquid phases + 1 vapor phase)
From the formula;
F = 3 – 3 + 2 = 0 + 2
F = 2
Yes they are stable because they follow octet rule but am not sure if they are exist separetly
The atoms are constantly in motion
Answer:
increased
Explanation:
I believe to be increased ,because the coal is a natural resource to be used.
i really hope it helps