Explain the tree radon gas sampling methods (3 of them)

How many moles of gas are present if p=11 atm, v=12l, t=185k?

Voltaic cells produce a positive overall charge. what does this indicate? a. the reaction is likely to be endothermic. b. the reaction is spontaneous. c. the reaction is not likely to occur. d. the reaction is not spontaneous.

Avariable that is not being directly tested during an experiment should be changed varied experimented controlled