Why do you think it is important not to get help with doing a pre-test

So that I can practice with it to get a good grade on the real test.(if I get anything wrong.)

In order to really learn from a pre-test, it's best to do all the work your self without any help from others. If you make a mistake, it is easier for your brain to absorb the information and learn.

the dissolution of polymer can be thermodynamically described in 2 steps.

the transfer of heat by electromagnetic radiation is called thermal radiation . it is usually carried out by electromagnetic waves in an energy range just below the visible spectrum, which is the infrared range.

so the answer would be radiation.

: )