How many moles of argon are present if there are 1.23 x 10^20 atoms?

2.04×10⁻⁴ moles of Ar

Explanation:

We begin from this knowledge:

1 mol of substance has 6.02×10²³ particles

Let's solve this by a rule of three:

6.02×10²³ atoms are contained in 1 mol of Ar

1.23×10²⁰ atoms must be contained in (1.23×10²⁰ . 1) / 6.02×10²³ =

2.04×10⁻⁴ moles of Ar

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:

what does the table look like