Which pair of atoms can form an ionic bond?
* na, k (sodium, potassium)
* k, f (potassium, fluorine)
* f, cl (fluorine, chlorine)
* na, ne (sodium, neon)

K, F (Potassium, Fluorine)

Explanation: Ionic bonds are formed by transfer of electrons between metal and non metals.

Covalent bonds are formed by sharing of electrons between non metals.

Electronic configuration of potassium:

Potassium atom will lose one electron to gain noble gas configuration and form .

Electronic configuration of fluorine:

Fluorine atom will gain one electron to gain noble gas configuration and form .

In potassium fluoride the one electron from potassium metal gets transferred to fluorine atom and thus form an ionic bond to give

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: