How did oxygen come up to make 21% of the earth's present atmosphere?

How many moles of nacl are required to make 250 ml of a 3.00 m solution?

What is the mettalliod in peiod three with more protons tha sodium and fewer valence electrons than chlorine?

Someone sprays perfume in another room. It can be smelled a few minutes later. What process is this an example of? A. osmosis B. diffusion C. active transport D. mitochondria

A penny has a total mass of 3.1 grams. Zinc makes up 2.9 g of the penny. What is the percentage of zinc in the penny?

Sound travels through a medium. Does sound travel in space? Explain why or why not:

Which type of bond would most likely be found in HBr

Which halogen is most likely to react? a. Br (bromine) b. F (fluorine) c. I (iodine) d. Cl (chlorine)

In the formula for water (H2O) what does the subscript 2 indicate?

Balance the nuclear reaction equation for the beta minus decay of nickel-63 by completing the missing numbers. The superscript of nickel is . The subscript of copper is .

What is the velocity of a BB pellet that is 0.02kg and has 36 J of KE