Question

Atom A has an atomic number of 19 and mass number of 40. Atom B has an atomic number of 20 and a mass number of 40. Which of these is an accurate statement?
A) Atom A has more protons than Atom B.
B) Atom A has one less proton and one more neutron than Atom B.
C) Atom A has an extra nucleon compared to Atom B.
D) Atom A has one more proton and one more electron than Atom B.

Answer 1

Atomic number indicates #P and mass number = P + N

So for atom A, P=19 and M=40, so N=21
For atom B, P=20 and M=40, so N=20

You can decide from here

Answer 2

B?

Answer 3

Yes