Which statements are correct about Avogadro’s constant? I. It is the number of ions in 12 g of sodium hydride, NaH.
II. It is the number of molecules in 22.4 dm-3 of hydrogen gas at 0 °C and 1 atm.
III. It is the number of atoms in 12 g of 12C

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 .

Ithink that one is (c)