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 
According to
Graham's Law of Diffusion," Diffusion of Gas is inversely proportional to square root of its Molecular Mass or Density".
rᵇ/rᵃ =

Or,
rᵇ/rᵃ =

----- (1)
As,
Ma = 275 g/mol
Mb = 205 g/mol
Putting Values in eq.1,
rᵇ/rᵃ =

rᵇ/rᵃ = 1.15
Result: Perfume B will diffuse 1.15 times faster than
Perfume A. Hence, Perfume B will be first smelled by the person.
Reactivity is not a physical property because it's a characteristic of a chemical element or compound and is involved in chemical process.
Answer:
The acid will be neutralized overtime
Explanation:
The presence of the pyrites leads to the leaching of large amounts of sulphuric acid, however the basic carbonates neutralizes the acid according to the reaction equation;
CaCO3 + H2SO4 ---> CaSO4 + CO2 + H2O.
This will prevent all the deleterious consequences associated with the leaching of the acid in the abandoned coal mine.
Answer:
The answer is
<h2>91.9 g</h2>
Explanation:
The mass of a substance when given the density and volume can be found by using the formula
<h3>mass = Density × volume</h3>
From the question
volume of copper = 10.3 mL
density = 8.92 g/mL
The mass is
mass = 8.92 × 10.3 = 91.876
We have the final answer as
<h3>91.9 g</h3>
Hope this helps you