7. How many chlorine atoms are in a 34.2 g sample of dichlorine pentoxide?

The answer to your question is 1.36 x 10²³ atoms

Explanation:

Data

number of atoms = ?

mass of the sample = 34.2 g

Molecule = Cl₂O₅

Process

1.- Calculate the molar mass of Cl₂O₅

Cl₂O₅ = (35.5 x 2) + (16 x 5) = 71 + 80 = 151 g

2.- Calculate the atoms of Cl₂O₅

                     151 g of Cl₂O₅ 6 .023 x 10²³ atoms

                       34.2 g of Cl₂O₅ x

                          x = (34.2 x 6.023 x 10²³) / 151

                          x = 1.36 x 10²³ atoms

the answers would be

the first one and the second one