Please answer this question pls! No bs thank you Please!!

Define dew point. i am writing this part to be able to ask the question

In the reaction between a crushed antacid tablet and vinegar what gas is emitted

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 !