56.56 Two chemicals react in an endothermic reaction. What can be known about this reaction?
O The new substance will need more energy to form its chemical bonds than the old substance will release.
O More energy will be released from the old substance than the new substance will need to form its chemical bonds.
O A precipitate will form as a result of the reaction.
O A gas will form as a result of the reaction.

Hot air balloons float in the air because of the difference in density between cold and hot air. in this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. to do this, use the following variables and make these assumptions: the combined weight of the pilot basket together with that of the balloon fabric and other equipment is w. the volume of the hot air inside the balloon when it is inflated is v. the absolute temperature of the hot air at the bottom of the balloon is th (where th> tc). the absolute temperature of the cold air outside the balloon is tc and its density is ďc. the balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. as always, treat air as an ideal gas. use g for the magnitude of the acceleration due to gravity.

Compare and contrast the bohr model and the electron cloud models of the atom.

The reactions of photosynthesis occur in the of plant cell? a.mitochondria. b. lysosomes. c. chloroplasts. d. chlorophyll