Can we round off atomic mass of copper to whole number and then solve in beggning will the ans be same is it ok to round off atomic mass of elements to whole number??

Dear student, no you can't round off the atomic mass of copper to 63g. You will have to take till 63.5g. You need to round off till tenth place. For example the atomic mass of carbon is 12.01g which can be taken as 12g while that Of chlorine is 35.45g which can be taken as 35.5g. Thanks and regards.