A)the mass of the earth is 6.0 x 10^24 kg. how many moles of 3.0 kg bricks would have the same total mass as the earth? b)a pure sample of 6.50 mol of a pure molecular substance has a mass of 0.234 kg. calculate the relative molecular mass of the substance and the number of molecules that would be contained in a pure sample of the substance of mass 0.500 kg. c)an empty room with internal volume 40 m3 contains air at atmospheric pressure (10a5 n m-2), at a temperature of 17 c. estimate the total number of molecules that make up the air in the room d) a cylindrical vessel is 0.50 m long and has a cross-sectional area of 1.0 x 10a-3 m2. the cylinder contains 2.0 x 10a-3 moles of oxygen. what is the magnitude of the total force that the oxygen gas exerts on one of the ends of the vessel when it has a temperature of 293 k? e)thirty moles of helium (mr 4) occupy a volume of 0.20 m3 at a pressure of 4.0 x 10a5 pa. if the volume is halved and the temperature is increased by 40 k, what is the new pressure of the gas?