# Tutor profile: Rafal E.

## Questions

### Subject: Chemistry

How many protons, electrons, and neutrons does carbon have?

On the periodic table, carbon is number 6. The number 6 is known as the atomic number of carbon. It is also equal to the number of protons of carbon. Protons are the positive charge. A carbon atom has to have 6 protons in order to be identified as a carbon atom. If an atom has 5 or 7 protons, it will not longer be a carbon atom. In order to cancel out the charge and be stable, carbon also needs to have 6 electrons. Electrons are the negative charge. 6 protons and 6 electrons make carbon a neutrally charged atom. (6-6=0) The number of neutrons varies between the different types of carbon. These ‘different types of carbon’ are known as isotopes. Neutrons are the neutral charge in an atom. For example, you can have carbon-12, which has 6 neutrons or you can also have carbon-13, which has 7 neutrons. The general rule to find the number of neutrons, is to subtract the number of protons from the atomic mass of the atom. For example, if you know that your atom has an atomic mass of 14 and your atom has 7 protons, the atom will have 7 neutrons (14-7=7). For carbon’s case, if you look at the periodic table, the atomic mass listed is ~12. So, if you subtract the number of protons (6) from the listed atomic mass (12), you will get 6 neutrons (12-6=6). In conclusion, an atom of carbon has: 6 protons 6 electrons 6 neutrons

### Subject: Biology

What is the process in which cells replicate and make identical daughter cells?

The process in which cells replicate and create identical daughter cells is called mitosis. Mitosis happens in all eukaryotic cells. In mitosis, the nucleus of the cell will divide in steps. In order, these steps are interphase, prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis. In interphase, the cell prepares for mitosis by replicating its DNA in the nucleus. In prophase, the chromatin (DNA) condenses and forms chromosomes. Each chromosome has two sister chromatids. In prometaphase, the nuclear envelope surround the chromosomes breaks down. In metaphase, the chromosomes align at the cell’s equatorial plate. In anaphase, the sister chromatids separate and the daughter chromosomes move to either side of the cell. In telophase, the nuclear envelope starts to appear around each daughter chromosome, creating two, new nuclei. In cytokinesis, the division of the cell’s cytoplasm occurs, creating two new cells identical to the mother cell.

### Subject: Algebra

5x + 3 = 7x – 1. Find x

In this math problem, it is telling us to find the value of ‘x’. What we will need to do in order to find it is that we first need to isolate it on one side of the equal sign. Here is one way you could solve this problem: 1). Add 1 to both sides of the equation. We are added the 1 (and not subtracting) because we need to do the opposite of whatever the sign is in order to cancel it out. On the right side, it will cancel the -1 and give us 0. On the left side of the equation, you will add the 1 to the 3. You cannot add the 1 to the 5x because there is no x attached to the 1 we are adding. If you do this correctly, you will get: 5x+4=7x 2). Now, in order to isolate the x to one side of the equation, we will subtract 5x from both sides. If you subtract 5x from the left side, you will end up with 0. If you subtract 5x from the right side, you will get 2x. If you do this correctly, you will get: 4=2x 3). Now you see, we have the x to one side of the equation but we are not done yet. The problem asks us to find the value of x, not 2x. So in this case, we will need to divide by 2 on both sides. Dividing by 2 on the right side, will give us 1. 1x and x are the same thing. If you divide 4 by 2 on the left side, you will get 2. If you do this correctly, you should get 2=x. Now, we have found the value of x.