21. thermal conductors don’t have to be hot to transfer heat. according to ch.16, (pearson physical science concept in action) explain a situation when an ice cube would still transfer heat to another object it is in contact with.

22. what is a medium?

use the following picture to answer question 31: (attached)
31. the bars in the drawing above are magnets. according to chapter 21, which of the following picture(s) is true? explain. then explain why the other 2 pictures are incorrect. make sure to explain all 3 sets.

32. based on how the book describes a heat pump in sec 16.3, how does a heat pump prove the law of conservation of energy? hint: think about a refrigerator.

The answers are as follows: 
21. A situation where an ice cube will transfer heat to an object that it is in contact with is the is the situation where you put an ice cube inside a warm drink. The ice cube that you put inside the warm drink will melt because, thermal heat from the drink moves into the ice cube; the drink thermal energy decreases while the ice cube thermal energy increases.
22. A medium of heat transfer refers to a substance, which acts as agent in a heat exchanger, through which heat is exchanged from one point to the other. The heat medium may be a liquid or a solid. 
31. The picture is option A is true. This is because, the magnetic field lines start from the correct origin, that is, from the north pole and they end in the south pole.
The picture in option B is not correct because, the magnetic field lines from outside the magnet start form the north pole. The magnetic field lines ought to start from the south pole and end in the north pole, not the other way round.
The picture in option C is incorrect because, magnetic field lines can not travel from a like pole to another like pole. The magnetic lines in this picture travel from the south pole to the south pole, which is not possible, because in physics, like do not attract like.
32. The law of conservation of energy states that energy can neither be created nor destroyed, it can only be transformed from one form to another.
A heat pump transfer heat from a cold area to a warm area. The energy that circulates in the heat pump system remains the same, but it is converted from one form to another form.