the density of ethanol is 0.789g/mL at 20 degree celsius. if 1.2 moles of ethanol are needed for a particular experiment, what vol. of ethanol should be measured out?

The molar mass of ethanol – CH₃CH₂OH is 46g/mol

i.e. 1 mol CH₃CH₂OH weighs  46 g

Therefore 1.2 moles of CH₃CH₂OH will weigh = 1.2 X 46 = 55.2 g

Now Density = Mass/ Volume

We are given that the density of ethanol is 0.789 g/mL. Therefore Volume of ethanol that is required will be 
   = Mass/ density
  = 55.2/ 0.789
  = 69.962 mL