4) When carbon disulfide burns in the presence of oxygen, sulfur dioxide and carbon
dioxide are produced according to the following equation:
CS2 + 3 O2 → CO2 + 2 SO2

a) What is the percent yield of sulfur dioxide if the burning of 25.0 g of carbon
disulfide produces 40.5 g of sulfur dioxide?

94.6% yield

Explanation:

42.8 g SO2  -> 100% yield

40.5 g SO2  -> x

x= (40.5 g SO2 * 100)/42.8 g SO2     x=94.6%

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.