What is the number of molecules in `0.25` moles of oxygen ?

Explanation

We know that :
`1` mole of oxygen contains `= 6.022 xx 10^(23)` molecules
So, `0.25` mole of oxygen contains `= 6.022 xx 10^(23) xx 0.25`
`= 1.505 xx 10^(23)` molecules
Thus, `0.25` mole of oxygen contains `1.505 xx 10^(23)` molecules.