In order for a carbon to be balanced it must have how many additional electrons added to its outermost shell

4 because it has 4 valence electrons aand it needs 4 electrons

Yes you are correct use the scientific method

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 .