The actual yield:

rarely equals the theoretical yield

always equals the theoretical yield

is always at least double the theoretical yield

is usually greater than the theoretical yield

rarely equals the theoretical yield

Explanation:

The actual yield is the result obtained from the experiment while the theoretical yield is the result obtained from our calculations. The actual yield of a chemical reaction rarely equals the theoretical yield because some of the amount are loss during the process.

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.