Which of these is an example of a chemical change?

What is the answer for the complicated molecules that make up living things usually contain carbon. why is carbon so important in these molecules?

Which best describes the scientific method? a. a path of clearly defined steps that must be followed in a particular order b. a possible answer to a scientific question based on knowledge or research c. the recipe for how to conduct an experiment that must be followed precisely d. the process of hypothesis and testing through which scientific inquiry occurs

Which tool could you see a plant cell? a. a filter b. a microscope c. a microwave d. an electromagnet