Which of the following is an example of gas?
a. pudding that is spooned from a pan into a cup
b. light that is spreads out to fill the space of a room
c. helium that fills a balloon, causing it to float
d. butter that starts as a cube and is spread on toast

C.hellium that fills a balloon causing it to float

sorry i was late, but i don't know what assignment your talking about, i'm in flvs as well, im in earth space science. but u are behind pace bc every class should be in the 3's or 4'

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.