Answer: option C. the number of electrons in the atom.
Given that the charge of a proton is the same that the charge of an electron, to be neutral the number of protons has to be the same than the number of electrons.
Explanation:
According to law of conservation of mass, mass of the reactants is equal to the mass of products in a chemical equation. As mass can neither be created nor it can be destroyed but it can be transformed from one form to another.
As it is given that hydrogen and in excess oxygen is reacting that leads to the formation of water. Hence, the chemical reaction equation will be as follows.

Since, it is given that 4 mol of hydrogen is reacting with excess of oxygen and gives 2 moles of water.
Hence, number of moles of water produced is calculated as follows.
4 mol of 
= 4 moles of 
Thus, we can conclude that 4 moles of water you can produce from 4.0 mol of hydrogen and excess oxygen.
Answer:
Explanation:
= Half-life of carbon = 5700 years
t = Time at which the remaining mass is to be found = 10400 years
= Initial mass of carbon = 11 g
Decay constant is given by

Amount of mass remaining is given by

The amount of the substance that remains after 10400 years is
.
I’m going to say the answer is most likely X because memetic energy is energy being used at that moment. Because the coaster is going fastest at X we can assume that the answer is X