As you add an acid to water, what ions are formed.
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Doing this increases the hydrogen ion consentration h+. when the acid is added to the water molecule constituting the acid HA is split into h+ and A- ions. The H + is produced this way combine with the H2O to form H3O+ or hydronium ions.

It increases as it goes hope this gives a bit of an idea?

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 .