Need help calculating atomic mass (see pohoto for more info)

28.1

Explanation:

Divide the percentage abundances by 100:

92.2% ÷ 100 = 0.922

4.7% ÷ 100 = 0.047

3.1% ÷ 100 = 0.031

multiply them by their corresponding mass number:

0.922×28 = 25.816

0.047×29 = 1.363

0.031×30 = 0.93

add them all together to get your final

25.816 + 1.363 + 0.93 = 28.109

to one decimal place:

28.1

I hope that helps!!!

28.1

Explanation:

The correct answer is 28.1

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.