Answer:

1. 197 g Au contains =6022×1023 atoms.

one molecule =6023×1022 atoms/ molecules.

∴2. 78×10−3 molecules of water contains =(278×10−3)

(6023×1023)

=1. 67×1021 molecules.

1. 0.05 g of H2O contain molecules =0.0518.0×6.022×1023=1.672×1021 molecules.

explanation

Answer:

heya!! here's the Answer, Answer pie!

1)Complete answer in the attachment.

2)Calculate the moles of gold (Au) in 1 g.

moles (n) = mass (m)/molar mass (M)

m(Au) = 1 g Au

M(Au) = atomic weight on the periodic table in g/mol = 196.967 g Au/mol Au

n(Au) = 1 g Au/196.967 g Au/mol Au = 0.005077 mol Au

Calculate the number of atoms of Au in 0.005077 mol.

1 mole of atoms = 6.022 × 10²³ atoms

0.005077 mol Au × 6.022 × 10²³ Au atoms/1 mol Au = 3 × 10²¹ Au atoms (rounded to one significant figure) .

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