<span>Very quick oxidation reactions result in combustion. Combustion happens when oxidation is fast. An example of combustion is the light batteries. We know that it is really dangerous if we will burn it because it has a fast oxidation process that can cause fire and its gas will explode.</span>
This problem is providing information about the initial mass of mercury (II) oxide (10.00 g) which is able to produce liquid mercury (8.00 g) and gaseous oxygen and asks for the resulting mass of the latter, which turns out to be 0.65 g after doing the corresponding calculations.
Initially, it is given a mass of 10.00 g of the oxide and 1.35 g are left which means that the following mass is consumed:

Now, since 8.00 grams of liquid mercury are collected, it is possible to calculate the grams of oxygen that were produced, by considering the law of conservation of mass, which states that the mass of the products equal that of the reactants as it is nor destroyed nor created. In such a way, the mass of oxygen turns out to be:

Learn more:
So potassium<span> is </span>more<span> reactive </span>than<span> lithium because the outer electron of a </span>potassium<span> atom is </span>further<span> from its nucleus </span>than<span> the outer electron of a lithium atom.</span>
Answer and
Explanation
I believe the correct answer would be the last option. When an electrons moves from an excited state to the ground state, it would release energy. An electron in the excited state would mean that it contains high kinetic energy so to move to a lower state some of these energy should be released.
I believe it is aluminum
<span />