3. Which statement about an atom is true:
A. All the elements have only one nucleon (mass) number.
B. The nucleon number can be less than the proton number.
C. The nucleon number can be equal to the proton number.
D. The number of neutrons never equals the number of electrons.
4. An element X has two isotopes, which may be represented by 238X and 235X. How does 238X
differ from 235X/
A. It has 3 more protons and 3 more electrons.
B. It has 3 more protons, but no more electrons.
C. It has 3 more neutrons and 3 more electrons.
D. It has 3 more neutrons, but no more electrons.
