In each of the following groups of substances, pick the one that has the given property.
Explain your reasoning for each.
a. Highest boiling point: HBr, Kr, or Cl2
b. Lowest vapor pressure at 25oC: Cl2, Br2 or I2
c. Lowest boiling point: CH4, CH3CH3, or CH3CH2CH3
d. Greatest viscosity: H2S, CH4, H2O2
e. Greatest heat of vaporization: H2CO, CH3CH3, CH4