Afellow student does not understand why air is a mixture. write a brief explanation about why air is a mixture, whether it is homogeneous or heterogeneous, and how it can be separated.

Air is a mixture because it consists of many different molecules (e.g. oxygen, nitrogen) however these different molecules are not chemically bonded to each other, they are simply circulating in the same space altogether. Generally, the different gases can be separated from the mixture by cooling air to a temperature below zero (not sure quiet what, about 180 degrees I think) so that the mixture is liquid. The liquid mixture is then passed through into a fractionating tower and gradually heated up- this process is called fractional distillation, and essentially the different substances in the liquid air mixture are separated and collected off as they all boil off at separate boiling temperatures as the mixture is gradually heated.

Not quite sure what you mean by the homogeneous/ heterogeneous part, but I'm sure someone else will have the answer. Hope this somewhat helps!

Air is a mixture because it consists of oxygen nitrogen and co2 it is therefore a homogenous mixture or solution and it can be seperated by a process know fractional distillation of liquid air. This is aprocess that converts air into a liquid form and then allows itto be portioned out

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 .