The hot, expanding gases generated by the combustion reaction in the
engines are:
O
A. used to move the wings.
O
B. used to provide lift for the airplane.
o o o
O
C. released through the back of the engine to propel it and the
airplane forward.
O
D. used to move the pistons, which help to propel the airplane.
o

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons

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.