Question

7.6•10^21 uranium atoms. What is the mass in grams

Answer 1

Moles of Uranium = 7.6x10^21/6.02x10^23 = 0.012 moles.

Mass of Uranium = moles x atomic mass of Uranium
                              = 0.012 x 238.029
                              = 2.85 grams.

Hope this helps!