Which of the following statements holds true for a chemical change?

a. in a chemical change, no new substance is formed
b. in a chemical change, a substance changes its phase
c. in a chemical change, the molecular structure of a substance changes
d. in a chemical change, one substance dissolves into another

Darla claims that the first periodic table developed by mendeleev was not completely accurate, so it is not useful at all. harmony argues that it establish the periodic table we use today, making it more credible. who is correct and why? darla is correct, because a model that has any mistakes should be thrown out. darla is correct, because a good model would not need to change. harmony is correct, because mendeleev’s model had all of the information correct in the first version. harmony is correct, because mendeleev’s model made predictions that came true.

Which best describes how johannes kepler developed his laws of planetary motion

Find the mass in grams of 1.37x1020 particles of h3po4