This question is asking us to determine how many atoms there are in  moles of . Rather than asking for the number of molecules, our final answer will need to tell us the number of atoms. Since there are  atoms for every molecule of , we'll first need to find out how many molecules there are.

0.70 (50 amu) + 0.25 (35 amu) + 0.05 (70 amu) = 47 amu = 47 g/mol

In this simplistic case, we only have two isotopes, so we know the following:

Where "n" represents the relative abundance of X-59, and "(1-n)" is the relative abundance of X-61. We will algebraically solve for "n":

simplifies to

simplifies to

which leads to

If "n" is equal to 0.515, that means the relative abundance of X-59 is 51.5%, and thus the relative abundance of X-61 is 48.5%.

A calculation would show that the relative abundance of each is 50%, you can see that 8.000 g/mol is exactly the midpoint between the masses of 7 and 9, so each has to be present in equal quantities.

In order to find the percentage of the lighter isotope in the natural sample, we need to use an equation that compares the percentage of each isotope and the natural molar mass. Since both of the isotopes together will account for 100% of the natural sample, we can say that the lighter isotope's percentage is , while the remaining percentage is .

Use this equation to solve for .

In other words, we can conclude that the lighter isotope makes up 40% of the natural sample. 

The abundance of  will be referred to as "n," and the abundance of  is "1-n." Together, we know that these values account for the full abundance of chemical X in existence.

The abundance of  is 96.25%, and the abundance of  is 3.75%.

This answer becomes a lot easier if we use some quick mental math. First, notice that if the two isotopes were equal in nature (50/50), than a mole would weigh 130 grams.

Since the number is less than that, we can conclude that isotope X is more dominant than isotope Y, lowering the average mass. Now, we can use math to find the exact percentage.

Start by realizing that isotope X will make up some percentage of the element in nature (we will call this percentage "A") while isotope Y will make up the rest of that percentage (1-A).

This means that 80% of the element is composed of isotope X, and the other 20% is composed of isotope Y. Going back to our mental math, we see that, just as we predicted, isotope X is present in a larger amount than isotope Y.

Protons, neutrons, and electrons are all subatomic particles. Alpha particles consist of 2 protons and 2 neutrons bound together in a particle. It is usually emitted during fission reactions. 

Electrons are notably smaller than nucleons (protons and neutrons), however, they have an equal amount of charge to protons. This is why an atom with the same amount of protons as electrons is considered electrically neutral.

The nucleus itself is positively charged, as the electrons are located relatively far away from the atomic center.

In an atomic representation, the number of neutrons and protons is the upper number
and the number of protons is the lower number. If only one number is given, we can assume
that the number of protons is its atomic number. Therefore (a) 7 protons and 8 neutrons
(b) 47 protons and 62 neutrons (c) 14 protons and 16 neutrons. The total number is 86.