Which best compares a molecule that has a trigonal planar shape with one that has a trigonal pyramidal shape?
they both contain three lone pairs of electrons around the central atom.
they both contain three atoms around the central atom.
the central atom of the trigonal planar molecule has two lone pairs around it, but the central atom of the trigonal pyramidal molecule has only one.
the central atom of the trigonal planar molecule has two atoms around it, but the central atom of the trigonal pyramidal molecule has only one.

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.

Esign techniques and materials that reduce the negative environmental impact of a structure are referred to as

Predict whether the changes in enthalpy, entropy, and free energy will be positive or negative for the boiling of water, and explain your predictions. how does temperature affect the spontaneity of this process?