When two substances are mixed and light is produced is it a chemical or physical change?

19. Why is slow-freezing so damaging to food compared to fast freezing?

How many atoms are in. 190g of P2O5?

Which set of quantum numbers is not permitted by the rules of quantum mechanics?

What time of the day would you be most likely to find that the air over water is significantly warmer

Which best describes the greenhouse effect? A) Nitrogen and oxygen in the atmosphere release heat. B) Water vapor and carbon dioxide in the atmosphere trap heat. C) Nitrogen and oxygen in the atmosphere trap heat.

The three major groups p On the periodic table are the

Which of the following has the greatest mass, in grams? a. 1 atom of lead (Pb) b. 0.5 mol copper (Cu) atoms c. 0.3 mol gold (Au) atoms d. 25 atoms of mercury (Hg)

Which one is not a sedimentery rock a.) sandstone b.) limestone c.) quartz d. (coal

Which group is more reactive than the alkaline earth metals?

Why do you not want any of the water on the outside of the test tube to drip off into the calorimeter?