Are these mixtures or pure substance?
1.water
2.blood
3.the oceans
4.iron 5.brass
6.uranium
7.wine
8.leather
9.table salt (nacl)

A mixture is a system that is made up of two or more substances which are not combined chemically. A pure substance is a system that only has one substance. The following are classified as:
1.water : pure substance
2.blood : mixture
3.the oceans : mixture
4.iron : pure substance
5.brass : mixture
6.uranium : pure substance
7.wine : mixture
8.leather : mixture
9.table salt (NaCl) : pure substance

True. It is the study of mankind's relationship to God and His environment.