Directions: On the line before each question or statement, write the letter of the correct answer. 1. Some substances are chemically combined in specific combinations. These are
A. compounds.
B. homogeneous mixtures.
C. heterogeneous mixtures.
2. Which item is a form of matter?
A. air
B. sound
C. gravity
3. Which item is a substance?
A. trail mix
B. table salt
C. breakfast cereal

Large asteroid and comet impacts. because they can have a huge impact on the environment, such as a loss of land, and crust on the earth with the big holes they produce. on the other hand, volcanic eruptions can also cause change within the environment by producing land, but im actually not quite sure which one would be a better answer, hopefully you read this and didnt just flat out choose the first sentence i have spoken! your welcome~

Dis the answer : ) good luck

Ithink scientist use creativity by asking questions about the natural world by using prior knowledge to solve problems.