Question

atom a has an atomic number of 19 and a 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 proton or neutron compared to atom b.
d atom a has one more proton and one more electron than atom b.

Explanation:

Step1: Define key atomic values

Atomic number = number of protons = number of electrons (neutral atom). Mass number = protons + neutrons.

Step2: Calculate protons for each atom

Atom A: Protons = 19; Atom B: Protons = 20

Step3: Calculate neutrons for each atom

Atom A neutrons: $40 - 19 = 21$
Atom B neutrons: $40 - 20 = 20$

Step4: Compare values

Atom A has 1 less proton, 1 more neutron than Atom B.

Answer:

B. Atom A has one less proton and one more neutron than Atom B.