3. Which of the following statements are correct? Rewrite incorrect statements to correct them,

(a) The atomic number always equals the number of protons.
(b) The atomic mass can be smaller than the atomic number.
(c) The mass number of an atom can be equal to the atomic number.
(d) The number of protons always equals the number of neutrons in an atom.
(e) The number of protons always equals the number of electrons in an atom.
(f) If the number of protons in an atom were changed, it would be a different element.