Baby Names Beginning With "A": Meaning: To Tie?

Questions

[science and technology] what is the name given given to the lowest temperature theoretically possible?

[science and technology] what is the mathematical term used to describe the shape of a cell in a honeycomb?

[science and technology] how many degrees are there in a circle?

[science and technology] what is the name given to the green pigment in plants?

[science and technology] what is the instrument used to measure atmospheric pressure?