Explain why and how adding heat to material will change its density?

If you add heat then the molecules will melt and, because of gravity, fall into a more densely packed material. This, of course, only works with inflammable objects.

when you add heat to a substance it causes certain parts of that substance to evaporate. look at water for instance when you add heat some of it turns to stem thus making its density lighter than before.

the major pests we deal with are insects, weeds and fungal diseases. a pesticide is a product, whether organic or chemical, used to kill the target pest. there are other techniques gardeners should use that can prevent the severe infestations that make the use of pesticides necessary

b. examine and describe cells