E85 fuel is a mixture of 85% ethanol and 15% gasoline by volume. what mass in kilograms of e85 (d = 0.758 g/ml) can be contained in a 14.0-gal tank?

Convert gal to liters:

               14.0 gal x 3.785 L / gal  =    53.0 L

Multiply volume by density  (the density would have the units of .758 g/mL   or  .758 kg / L)

               53.0 L    x   .758 kg/L    =    40.2 kg

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.