Calculate the number of moles in
(i) `12.046xx10^(23)" atoms of copper"`
(ii) 27.95 g of iron
(iii) `1.51xx10^(23)" molecules of "CO_(2)`

Explanation

(i) `12.046xx10^(23)" atoms of copper"`
`6.023xx10^(23)" atoms of copper = 1 mole"`
`therefore 12.046xx10^(23)" atoms of copper"=(1xx12.046xx10^(23))/(6.023xx10^(23))="2 moles of copper"`
(ii) `"27.95 g of iron"`
`"55.9 g iron = 1 mole"`
`therefore" 27.95 g of iron"=(1)/(55.9)xx27.95="0.5 mole of iron"`
(iii) `1.51xx10^(23)" molecule of "CO_(2)`
`"No. of moles"=("No. of molecules")/("Avogadro number")`
`=(1.51xx10^(23))/(6.023xx10^(23))="0.25 mole of "CO_(2)`