If the temperature of a gas changes, but the number of moles and volume remain constant, which of the following values must also change?
Density
Pressure
Number of atoms
Mass

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 .

They make up examples of physical properties 

Reducing agents  oxidized by the reaction 

She was of necessity running a grass roots target audience was unlettered