Which describes bohr’s contribution to the atomic model? a. he described electrons in specific orbits around the nucleus. b. he determined that atoms are neither created nor destroyed. c. he recognized that an element could have several isotopes. d. he predicted the existence of elements that had not yet been discovered

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .