What is the theoretical yield of SO3 produced by 2.15 g of S?

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.

Robert leaves a chocolate bar in his car while attending school all day. when he goes to his car in the afternoon, the bat has changed into gooey liquid. what happened to the chocolate bar

The density of e85 fuel is 0.801 g/ml. what is the mass of 1.00 gallon of the fuel? (1 gal. = 3.785 l)