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Question
Which has more atoms, 50 g of aluminium or 50 g of iron ? Illustrate your answer with the help of calculations.
(Atomic masses : Al = 27 u ; Fe = 25 u)
Solution
Mass of aluminium = 50g
We know that 27g of aluminium contain 6.022 × 1023 aluminium atoms
Number of aluminium atoms in 27g aluminium = 6.022 × 1023
Number of aluminium atoms in 50g aluminium = 50 × 6.022 × 1023/ 27
Hence, 50g aluminium has11.15 × 1023 atoms.
Mass of iron = 50g
We know that 56g iron contain 6.022 × 1023 atoms
Number of atoms in 56g iron = 6.022 × 1023
Number of atoms in 50g iron = 50 × 6.022 × 1023 / 56
Hence, 50g iron comprises 5.376 × 1023 atoms.
It is clear that more number of atoms is present in 50g aluminium than 50g iron.
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