Which of these is an indication that a chemical reaction occurred

a. formation of gas
b. boiling of a substance
c. melting of a substance
d. freezing of a substance

What is the mass defect of a mole of nuclei with 1.8 x 10^15 j/mol binding energy?

How many moles are in 7.2 x 10^23 carbon molecules? (*round to the nearest hundredth and include the unit "mol c" after your number) question 6 options:

Which type of precipitation would most likely form when the surface air temperature is slightly below freezing and the air temperature increases as you move upward away from the ground?