What are two substances that are chemically combined to produce a substance and water.

Researchers randomly divide participants into groups. each group takes a different amount of omega-3 fatty acid supplements daily for a month. one group receives a placebo. the researchers measure the impact on cholesterol levels in the blood. what is the purpose of random assignment in this experiment? a, to produce treatment groups with similar characteristics b, to ensure that all people with high cholesterol have an equal chance of being selected for the study c, to increase the accuracy of the research results and prevent skewness in the data

Explain why it’s important for scientists to study the sun. list at least two challenges researchers face when examining earth’s nearest star.

The changes that the students observed, rapid breathing and sweating, would be classified as a to a change in a system.