Ms. brown's class is learning about physical and chemical changes. after reading the passage, the students had to pick out the model of the physical change. can you them? pick the correct model and give a reason for your choice.

If you chip a tooth, most likely you will go to the dentist to have the missing material filled in. currently the material used to fill in teeth is a polymer that is flexible when put in, yet is hardened to the strength of a tooth after irradiation with blue light at a wavelength of 461 nm. what is the energy in joules for a photon of light at this wavelength?

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.

How many moles of water are created if 3 moles of hydrogen react completely with excess oxygen?