Combustion vapor-air mixtures are flammable over a limited range of concentrations. the minimum volume % of vapor that gives a combustible mixture is called the lower flammability limit(lfl). generally, the lfl is about half the stoichiometric mixture, the concentration required to complete combustion of the vapor in air. a) if oxygen is 20.9 vol % of air, estimate the lfl for n-hexane, c6h14. b) what volume of c6h14(d=.660g/cm^3) is required to produce a flammable mixture of hexane in 1.000m^3 of air stp?

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.  

i have no clue hope you find the answer