Hey there!
Atomic number is the number of protons.
Atomic mass is the sum of protons and neutrons.
9 + 11 = 20
Your answer is B) The atomic number is 9 & the atomic mass is 20.
Hope this helps!
The correct answer for the following questions that are presented above are these ones:
(1) b. Pressure. The <span>physical effect can change the boiling point of a substance is the pressure.
(2) </span><span>Evaporation only occurs at the surface of a liquid. TRUE.</span><span>
(3) </span>d. freezing. The change from liquid to solid, or the reverse of melting, is called freezing.
Condensation because the water vapor has a high entropy(disorder) and liquid water has a lower entropy.
the answer is D. just took the test
It's not the protons neutrons or electrons I know for sure but not the energy levels but it's the only one left so it has to be
