All of the statements about nuclear reactions are true except

• A

  $\text{ Nuclear reactions involve changes in the nucleus of an atom}$

• B

  $\text{ The rate of a nuclear reaction is increased by the addition of a catalyst}$

• C

  $\text{ A nuclear reaction is unaffected by the chemical state of the atoms involved}$

• D

  $\text{ Nucloar roactions of the same element văry according to which isotope is involved }$