Of elements in the same group, those at the bottom of the periodic table have low ionization energies because
A. these elements are high in electronegativity
B. they have fewer electron shells to shield the protons from the
electrons
C. their atomic radius is large
DD. layers of electron shells shield the protons' attractive force

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 .