Questions

angstrom is used to measure wave length,

weber is used to measure Magnetic flux,

lux is used to measure Intensity of illumination.

Arunachal Pradesh State has been declared as the Open Defecation Free state.

A greenhouse gas is a gas in an atmosphere that absorbs and emits radiant energy within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. 

Carbon dioxide is a main greenhouse gas, found in car exhaust pipes.
Methane and nitrous oxide is another type of greenhouse gas.

Oxygen is the only clean gas out there because we need it to survive. Therefore, the only gas that is not a greenhouse gas is Oxygen.