How many millimeters of cl2 gas must you have to obtain 0.20 g at STP?

STP = Standard Temperature (273 K) Pressure (1 atm)we also have the mass of cl2, 0.2g. We use this to find the number of moles.Use the ideal gas law.PV = nRTP= pressure in atmV= volume in Litersn = number of moles of gasR = 0.082058T = Temperature in KelvinP = 1 atmV = ? (we are looking for this)n = moles   = mass/molar mass   = 0.2g/(2*35.453)   = 0.0028 molesR = 0.082058T = 273 K(1)V = (0.0028)(0.082058)(273)V = 0.063 L= 60 mL (1 sig fig)good luck!