Number 7 please I’m struggling

One mole of hydrogen has a number of molecules equal to the Avogadro Constant or 6.022* 10^23. 1.06 moles of hydrogen is equal to 6.022* 10^23* 1.06 = 6.38*10^23 molecules. Therefore the number of molecules of hydrogen that 48.7 g of sodium added to water yields is 6.38*10^23.

The density would be 1.622

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 .