Nitrogen and oxygen are gases in the atmoshere.

trace
variable
primary
rare

Nitrogen and oxygen are primary gases in the atmosphere.  

Trace  

Variable  

Primary  

Rare

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.

the answer is 303.15 or 303