Why does the hygrometer need to be calibrated before it is used?

What is the concentration of water in an egg? Why did Dr Montessori give an illustration of the work of the tiny polyp? How do you pass a spit test? Food being warmed by infrared light is heat transfer by? What does hypothesis and theory have in common? What part did Erasmus play in the Renaissance? What glue is best for rubber? How many cups is 300 milliliters? Is humidity a mixture compound or solution? What is the term used to describe the process in which light is produced by rubbing materials together? Are substantiated claims are more willing accepted by the denialist politicians lawyers or the skeptic? What happens when you add water to vegetable oil? What part of the onion plant serves as storage organ? What happens to the rod when it is rub by nylon? Why do they call it junk science? A sound wave that carries a lot of energy and has a large amplitude has a lot of? Why do only some parts of the ammonite get fossilised? What Chianti has straw around the bottle? Which biome has warm summers cold winters receives at least 50 cm of rain per year trees shed their leaves and grow new ones each year? Why darkness become the real killer after the asteroids impact on earth?