Question

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Answer 1

Answer:

1. the number of atoms of Zn present in the 10g Zinc piece is 9.3×10²².
2. the mass of one atom of oxygen is 2.656×10⁻²³ g
3. 50g Al contains more atoms than 50g Fe
4. the number of moles of 34.5g Na is 1.5 moles

Explanation:

Number of moles = given weight / GAM

         where GAM = Gram Atomic Mass

Number of atoms = Number of moles × Avogadro's number

         where Avogadro's number =  6.022×10²³

• Zinc

           weight of Zn = 10g

        Atomic weight = 65u

                       GAM = 65g/mol.

       Number of moles  = 10/65 = 0.15mol.

      Number of atoms   = 0.15 × 6.022×10²³ = 9.3×10²²

Thus, the number of atoms of Zn is 9.3×10²².

• Oxygen

         1 mole O weighs 16g

         1 mole O contains 6.022×10²³ O atoms

           So, 6.022×10²³ O atoms ≡ 16g

         mass of 1 O atom = 16g / 6.022×10²³  = 2.656×10⁻²³ g

Thus, the mass of one atom of oxygen is 2.656×10⁻²³ g

• Aluminium and Iron

            GAM of Al = 27g

          GAM of Fe = 56g

         moles of Al = 50/27 = 1.85mol.

         moles of Al = 50/56 = 0.89mol.

Since the number of moles of Al is more, Al contains more atoms.

• Sodium

                 mass of Na = 34.5g

     atomic mass of Na = 23u

                 GAM of Na = 23g/mol.

               moles of Na = 34.5/23 = 1.5mol.

Thus, the number of moles of Na is 1.5 moles