Answer:
The forces acting on the book are balanced by each other.
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.
The balanced chemical equation for reaction of potassium superoxide with carbon dioxide to produce oxygen and potassium carbonate will be:

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Explanation:
As per Brønsted-Lowry concept of acids and bases, chemical species which donate proton are called Brønsted-Lowry acids.
The chemical species which accept proton are called Brønsted-Lowry base.
(a) 
is Bronsted lowry acid and
is its conjugate base.
is Bronsted lowry base and
is its conjugate acid.
(b)

is Bronsted lowry base and HCN is its conjugate acid.
is Bronsted lowry acid and
is its conjugate base.
(c)

is Bronsted lowry acid and
is its conjugate base.
Cl^- is Bronsted lowry base and HCl is its conjugate acid.
(d)

is Bronsted lowry acid and
is its conjugate base.
OH^- is Bronsted lowry base and
is its conjugate acid.
(e)

is Bronsted lowry base and OH- is its conjugate acid.
is Bronsted lowry acid and OH- is its conjugate base.