1) Answer is: D. Writing a hypothesis.
The scientific method is a process for experimentation that is used to explore observations.
Steps of the scientific method:
1) ask a question about something that is observed.
2) do background research.
3) construct a hypothesis, an attempt to answer questions with an explanation that can be tested.
4) test of hypothesis.
5) analyze collected data and draw a conclusion.
2) Answer is: A. Carbon and oxygen are chemically bonded in it.
A compound (in this example carbon dioxide CO₂) is a pure substance because its molecule cannot be broken down into simpler particles by physical means.
A chemical compound is a chemical substance composed of many identical molecules composed of atoms held together by chemical bonds.
Carbon dioxide (CO₂) are inorganic compounds with covalent bonds between carbon and oxygen.
3) Answer is: B. Components that are mixed can be in different states of matter.
A single substance can be used to make a mixture if the substance is composed of more than one element is not correct, because mixture is composed of at least two substances. For example mixture of water and alcohol ethanol.
There is a definite recipe to make each mixture, so the composition of a mixture is set is not correct, because composition of mixture can vary.
Components that are mixed can be in different states of matter is correct, for example mixture of salt (solid) and water (liquid).