Question

from 2mg calcium 1.2×10^19 atoms are removed.the no of g atoms of calcium left is

Answer 1

Heya...

Here is your answer...

-) Mol at first:

= m/Ar

= 2/40

= 0.05 milimoles

-) Number of atoms at first:

= n x L

= 0.05 x 10^-3 x 6.02 x 10^23

= 3.01 x 10^19

-) Number of atoms after it was removed:

= (3.01 - 1.2) x 10^19

= 1.81 x 10^19 atoms

-) Mol after it was removed:

= (1.81 x 10^19)/(6.02 x 10^23)

= 3 x 10^-5 moles

-) No. of gram atoms:

= n x Ar

= 3 x 10^-5 x 40

= 120 x 10^-5 grams

= 1.2 miligrams.

Thanks...!!!

XD

Sorry baby 'wink'