Question

The atomic mass of an element whose atoms consist of eight protons, nine neutrons, and eight electrons is ?

Answer 1

number of protons = atomic number
protons + neutrons = mass number

Answer 2

\[m(element)=8*m(proton)+9*m(neutron)+8*m(electron)\]
Assume just to make it more easy that:
m(proton)=m(neutron)=1 u*
m(electron)= 1/1000 u
1 u=*1,66053886 · 10^-27 kg

Answer 3

It is a isotope remember that.

Answer 4

beside the 15.9994 is the average mass of the natural occurring isotopes multiplied with their relative percentage of appearance :)

Answer 5

them it's 16.99913170 amu :P

Answer 6

anyway it would be something close to 17 as 8+9 = 17 :P