Monica and Alexis are doing an experiment in science class with baking soda and vinegar. Their teacher is happy with the results of their experiment; however she wants to make sure
that the students can get the rest of their trials done before the end of class. What is one
way that Monica and Alexis can speed up the reaction without affecting the results?
They can add more baking soda.
There is not way for them to speed up the reaction.
They can add ice to the vinegar to decrease its temperature.
They can do the experiment on a hot plate to increase the temperature.

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.