Why can scientists ignore the forces of attraction between particles in a gas under ordinary conditions

Scientists ignore the forces of attraction between particles in a gas under ordinary conditions because the particles in a gas are apart and moving fast, rather than clustered and moving slow, therefore the forces of attraction are too weak to have a visible effect.

Where are the questions

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 .