Question

Question #91b45

Answer 1

`9.41` x `10^21` molecules

Explanation:

`16` grams of Oxygen atom = `1` mole
`1` mole = `6.023` x `10^23` molecules
`16` grams of Oxygen atom have molecules = `6.023` x `10^23` molecules
`0.25` g of Oxygen atom will have molecules = (`6.023` x `10^23` molecules) x `0.25` g]/`16` g = `9.41` x `10^21` molecules

OR
Oxygen = `0.25` g
molar mass = `16` g
no. of moles = `0.25/16` = 0.0156 moles

`1` mole = `6.023` x `10^23` molecules
so, `0.0156` moles of Oxygen atom = `0.0156` moles x `6.023` x `10^23` molecules = `9.39` x `10^21` molecules = `9.4` x `10^21` molecules