Question

The atomic mass of calcium is 40u.what will be the number of calcium atom in 4.0 g of calcium?

Answer 1

1 amu = 1.66056 × 10−24 g.
The mass of single atom of Ca is 40 u
​But the mass of 1 mole of Ca atom is 40 g
​or Mass of 6.023 x 1023 atom = 40 g
​So we calculate generally the number of atom , if mass of the sample is given in gram like as:
number of atoms in 0.4 gram of Ca sample = 0.4/40  x 6.022 x 1023 = 6.022 x 1021 of Ca 

Answer 2

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