Question

calculate the no.of cu atoms present.in 10 grams of bell metal which consists of 80%cu and 20%sn

Answer 1

10 gms of bell metal will contain 8 gm cu ( since it constitutes 80% of it)

So, moles of copper present

n = w/MM = 8/63.5 = 0.1259 moles

No. of cu atoms present= n x Avogadro's no.

= 0.1259* 6.022 * 10^23

= 0.758 x 10^23

or

7.58 x 10^22