When 200 grams of water cools from 50.C to 25C , the total amount of heat energy released by the water is ? A. 42 kJ
B. 21 kJ
C. 34 J
D. 17 J

1) which of the following is the best example of a physical change? a) sugar dissolving in tea b) firefly glowing 2) in the combustion of ethane, what is/are the reactants? c2h6 + o2 ==> co2 + h2o a) c2h6 and o2 b) co2 and c2h6

How could a student test the effect of removing heat from a gas that is stored in a sealed container? what must occur in order for matter to change states?

What is the molarity of the solution produced when 145 g of nacl is dissolved in sufficient water to prepare 2.75 l of solution?