Answer:
A.
Explanation:
The amount of mass always stays the same, matter cannot be created nor destroyed, it can only change forms. Thus, the answer is A.
I'd guess A or D, but my gut says A
Stirring affects how quickly a solute dissolves in a solvent, but has no effect on how much solute will dissolve. The amount of solute that will dissolve is affected by temperature - more will dissolve at higher temperatures. This is called the solubility of the solute
For example phosphorus and oxygen can covalently bond to form a polyatomic ions, PO4³⁻ and PO3³⁻.
Answer:D. Nitrates
Explanation:
Nitrates enter the environment from fertilizers, sewage, or human and animal waste.
Therefore
Farms, golf courses and domestic gardens blame nitrates for contamination.