Answer:
NaOH
Explanation:
The sodium hydroxide is strongest base because it fully dissociate into ions.
It dissociate to gives the sodium and hydroxyl ions and solution became more basic.
NaOH → Na⁺(aq) + OH⁻(aq)
Its pH is 12. It is also known as caustic soda.
Other given Options:
The pH of blood is vary from 7.35 - 7.45. it is slightly alkaline.
The pH of HCl is 3.
The pH of saliva is 6.2 - 7.6.
We know that neutral pH is 7 the pH less than 7 is acidic so HCl is acidic because its pH is 3.
The pH is greater then 7 is basic so saliva and blood are basic but less than the NaOH.
Answer: The green copper (II) carbonate
changes to black copper oxide 

Explanation:
Decomposition is defined as the chemical reaction in which a single compound gives two or more simple substances. It requires energy to break the bonds between reactants, thus is an endothermic process.
Thermal decomposition uses heat for decomposition.
The chemical equation for thermal decomposition of copper (II) carbonate is:

The green copper (II) carbonate
changes to black copper oxide 
<span>I believe an oxidation reaction is occurring</span>
Answer:
a formula giving the proportions of the elements present in a compound but not the actual numbers or arrangement of atoms.
Explanation:
Because it is made up of sodium, a metal, and carbon, a nonmetal.
Hope I helped ♡