Which is evidence that a chemical reaction has occurred

Adoctor is trying to diagnose a patient with dry skin. which of the following resources would be the most ? a magazine ad about soft skin a growth chart online articles about dry skin medical books

The large increase in atmospheric carbon dioxide in the last 50 years most likely comes from a. an increase in cellular respiration b. increased decomposition by bacteria c. an increase in the burning of fossil fuels d. an increase in photosynthesis

Which statement describes compounds a. compounds are made of one type of atom. b. compounds cannot be represented by models. c. compounds are represented by chemical formulas. d. compounds cannot be broken down into simpler forms.