When you have finished adding the necessary amount of naoh to your beaker, what color will the litmus paper turn?

The red litmus paper turns blue on dipping in NaOH solution.

Explanation:

Litmus paper is the indicator that detects the nature of the solution, whether it is acidic or basic.

There are 2 types of litmus paper:

NaOH is a strong base, so when a red litmus paper is dipped in the beaker having necessary amount of NaOH, the red litmus paper turns into blue.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.