Matter appears to be conserved in chemical reactions but not in nuclear reactions because:
a. the law of conservation of matter only applies to a limited number of chemical and nuclear reactions
b. the law of conservation of mass-energy applies only to nuclear reactions
c. in nuclear reactions, particles move too quickly to have their masses measured
d. in nuclear reactions the changes in mass are large enough to be detected
i think it's a? just tell me if i'm right, and if i'm wrong, point me in the right direction : )