Is a system that contains only one substance necessarily homogeneous

How many miles of calcium oxide will be produced when 1.6 miles of iron (iii) oxide react with calcium phosphate

0.2348 grams of pbcl2 used to form 44.0 ml of solution.

The human activities in two locations are described below: location a: rampant use of plastic containers location b: excessive use of pesticides and fertilizers which statement is most likely true? location a will have poor air quality because plastic is biodegradable. location a will experience water scarcity because plastic absorbs moisture. the population of honeybees will increase in location b because production of crops will increase. the population of fish in location b will decrease because the water is contaminated.