4Na + O2 = 2Na2O if you use 18 grams of O2 how many grams of Na will you have to also use to make the reaction work​

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?

Diffraction is when light is bent around obstructions. which of the these observation about clouds would indicate diffraction? a) after rain storms, you can sometimes see rainbows. b) clouds are white or gray and cannot be seen through. c) on a cloudy day, the temperature tends to be cooler than a sunny day. d) the edges of dark clouds appear lighter. this

Define a is a tiny pavket of energy