What is the percentage by mass of Mg in MgO

The mass of a neutron is equal to the mass of a proton plus the mass of an electron. true or false false true

At 300 mm hg, a gas has a volume of 380 l, what is the volume at standard pressure

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