________is a transparent, tasteless, odourless, chemical substance.

________is called ornamental stone

Plastic bottles are formed from a chemical substance ………. .

………………… is a transparent layer .

________ are substances that speed up the process of a chemical change and it will not under go any change during the course of the reaction

The endocrine glands produce chemical substances called___.

Assertion: Nuptial flight is a unique flight taken by the queen bee followed by several drones. Reason: The queen bee produces a chemical substance called pheromone. The drones in that area are attracted to the pheromone and then mating takes place.