4.6*10²²atoms of an element weighs 13.8g.what will be the atomic weight of that element?

Dear Student,

Atomic weight of an element = Mass (g) of that element in 1 mole

We know that, 

1 mole of an element = 6.023 x 10²³ atoms .

If 4.6 x 10²² atoms of an element weigh 13.8 g

∴ 6.023 x 10²³ atoms of that element will weigh (6.023 x 10²³ x 13.8 g) / (4.6 x 10²²) = 180.69 g.

Therefore,

1 mole of an element weighs 180.69 g, so

Atomic Weight of the element = 180.69 g

Hope its clear now.

Enjoy learning!!