Question

no. of atom in 120 g of calcium

Answer 1

40 g of Ca = 1 mol
120 g = 120/40 = 3 mol ans

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Answer 2

Mass of calcium given = 120g

Molecular mass of Calcium = 40 amu

So molar mass of Calcium= 40g

In 40g, there is 1 mole of calcium.

in 120g, amount of calcium = 120/40 = 3 moles

Number of atoms in 1 mole = 6.022 × 10^23

Number of atoms in 3 moles = 3 × 6.022 × 10^23 = 1.806 × 10^24

Thus, there are 1.804 × 10^24 atoms in 120g calcium.