An element that has the same chemical properties as other atoms of that element, but that has a different number of neutrons is a(n):
a. isotope
c. substance
b. compound
d. covalent element

Using mr smith and his id, identify two potential internal validity threats that might affect the a—b design. tell me how that threat might impact conclusions in the a—b design. note #1: you cannot use maturation (since i already did that one for note #2: there are some mr smith id threats that won’t have much impact in a single case design.