Question

What is the atomic weight of an element X for which a sample containing `1.58xx10^(22)` atoms weigh 1.05 g?
A. 28 g
B. 20 g
C. 40 g
D. 23 g

Answer 1

Correct Answer - C
We know that one mole of an element
`= 6. 02 xx 10^(23)` atoms
= atomic weight of the element
Now, `1.58xx 10^(22)` atoms weigh `.05` g
`therefore 6.02 xx 10^(23)` atoms weigh `= ((1.05xx6.02xx10^(23)))/(1.58 xx 10^(22)) = 40 ` g
Atomic weight of `X=40` g