Intermolecular Forces and Physical Properties of Pure Substances

Which has the highest normal freezing point?
a. O2
b. N2
c. H2
d. NH3
Which has the lowest enthalpy of fusion?
a. H2O
b. Li2O
c. HCl
d. HF
Which has the least heat of vaporization?
a. H2Te
b. Xe
c. H2Se
d. H2O
Which has the highest normal boiling point?
a. C2H6
b. NH3
c. Li2O
d. CH4
Which has the smallest vapour pressure at 25°C?
a. O3
b. SiO2
c. CO2
d. H2O

b

Explanation: because b is the right one i just did it.

the grams   of   barium that   are in   2.3 x 10^23   atoms of barium   is   52.4 g (answer c)

    calculation

mass = moles   of ba   x molar   mass of ba

  molar mass of ba from periodic table=   137.3 g/mol

  use the   avogadro's law   constant   to   calculate the moles of barium

  that   is     1 mole =   6.02   x 10^23 atoms

                    ? moles = 2.3 x 10^23   atoms

by cross   multiplication

=(1 mole   x 2.3x 10^23 atoms)   / 6.02   x10^23 atoms)=   0.382   moles

mass   is therefore = 137.3   g/mol x 0.382 mol = 52.4 ( answer c)

explanation: