Question:
Use evidence from the fact that if one mineral can scratch another mineral then that other mineral is softer than that one mineral to answer the following question. "To discover how tough a certain mineral may be, one would"

Answer:
attempt to leave a mark on it

Question:
Use evidence from the fact that if the population of an organism increases then the ecosystem may become overpopulated with that organism to answer the following question. "Invasive plants in an ecosystem often lead to"

Answer:
overpopulation

Question:
Use evidence from the fact that rocks sometimes contain iron to answer the following question. "Iron can be found on"

Answer:
rocky areas