At a temperature of 273 k, the syringe contains 11.0 cm3 of air. how many moles of air are in the syringe?

According to Geankoplis,2003, the density of air at 1 atm and and 273 K is 1.293 kg/m³. This is equivalent to 0.001293 g/cm³. The molar mass of air is approximately 29 g/mol. To solve this,

11.0 cm³ * (0.001293 g/cm³) * (1 mol/29 g) = 4.9 x 10^-4 mol of air

The objects are acted upon by only one force. gravity. mass times the acceleration of gravity (-9.81meters/second squared).