What causes the difference in bond angles in carbon dioxide and water?
a) the distance between the atomsin either molecules
b) the facr that there are tei oxygen atoms in carbon dioxide and only one in water
c) the fact that the number of lone pairs of electrons on the central atom is greater in the case of water
d) the presence of a carbon atom in carbon dioxide
e) the presence of a hydrogen atom in water

I would say the answer is C. The number of lone pairs of electrons on the central atom is greater in the case of water.

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:

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.