Answer:
A. increases
Explanation:
According to the Gay-Lussac's law:-
Thus, at constant volume and number of moles, Pressure of the gas is directly proportional to the temperature of the gas.
P ∝ T
Also, it can be written as:-

Thus, if the temperature is increased, the pressure exerted by the gas also increases.
Density is the weight of something per unit of volume
Answer:
a :Chemical b : compound
Explanation:
a : it had to be a chemical change because it says "There is no change in
the appearance of the solid, but the reactivity of the material changes.
b : well it would be a compound because it would have to be to make a reaction