Use the drop-down menus to complete the statements. investigations allow for the control of variables and can be repeated. investigations are usually less time-consuming and less expensive. investigations make it possible to study a wide range of variables.

Astudent is given a sample of a blue copper sulfate hydrate. he weighs the sample in a dry covered porcelain crucible and got a mass of 23.875 g for the crucible, lid, and sample. the mass of the empty crucible and lid was found earlier to be 22.652 g. he then heats the crucible to expel the water of hydration, keeping the crucible at red heat for 10 minutes with the lid slightly ajar. on colling, he finds the mass of crucible, lid, and contents to be 23.403 g. the sample was changed in the process to very light clue anhydrous cuso4. if there are again 100.0 g of hydrate, how many grams of cuso4 are in it? how many moles of cuso4? (hint: molar mass of cuso4 = 159.6 g / mole. what per cent of the hydrate is cuso4? you may convert the mass of cuso4 to moles.)

Atoms contain subatomic particles called protons and neutrons. when these protons and neutrons spilt, a lot of energy is released

Select the correct location on the image identify the element that humans need to breathe. 2015 er r ights reserved