How many lone pairs of electrons are on nitrogen in nf3?

Which fact represents evidence for the big bang theory?

How could a student test the effect of removing heat from a gas that is stored in a sealed container? what must occur in order for matter to change states?

Need what is special about water as a compound? how does water regulate climate? what drives water evaporation?   why is the water vapor fresh water when it rises from the ocean? why might freshwater in the form of snow take longer to enter the water cycle again than liquid precipitation?   what is an aquifer? what role do people play in the water cycle? plz just answer as many as you can ! thx if you !