question:
During a lab investigation a scientist heats a solid substance. The scientist observes that the solid has two different melting points. The scientist is able to separate the two resulting liquids. Which statement best classifies the original solid substance?

answer:
It was a mixture.

question:
Moving water in a river is considered a renewable resource because it

answer:
can be recycled by nature over time

question:
Which of the following is an example of an assistive device?

answer:
contact lens

question:
Light travels fastest through which of the following?

answer:
a vacuum