1 significant figure, because there is no decimal after the zero the zero doesn't count.
Answer:
I think its carbon because of all the chemicals being used in that air.
Answer: 0.5 g/cm^3
Density equals mass divided by volume so..
60/120 is 0.5 g/cm^3
0.091 moles are contained in 2.0 L of N2 at standard temperature and pressure.
Explanation:
Data given:
volume of the nitrogen gas = 2 litres
Standard temperature = 273 K
Standard pressure = 1 atm
number of moles =?
R (gas constant) = 0.08201 L atm/mole K
Assuming nitrogen to be an ideal gas at STP, we will use Ideal Gas law
PV = nRT
rearranging the equation to calculate number of moles:
PV = nRT
n = 
putting the values in the equation:
n = 
n = 0.091 moles
0.091 moles of nitrogen gas is contained in a container at STP.