The diagram below shows a stack of five coloured circular disks made of smooth, polished wood. Describe the motion of the coloured disks when the plunger is hit quickly and firmly by the hand.

The vapour pressure of benzene is 53.3 kpa at 60.6 °c, but it fell to 51.5 kpa when 19.0 g of a non-volatile organic compound was dissolved in 500 g of benzene. calculate the molar mass of the compound.