Element X has two isotopes. The table gives information about these isotopes.

Isotope Atomic Mass (amu) Abundance (%)

X-63 62.9296 69.15

X-65 64.9278 30.85

The average atomic mass of element X is

amu.

Average Atomic Mass = 63.5460 amu

Explanation:

Data Given:

Atomic Mass of ⁶³X = 62.9296 amu

Natural Abundance of ⁶³X = 69.15 %

Atomic Mass of ⁶⁵X = 64.9278 amu

Natural Abundance of ⁶⁵X = 30.85 %

Formula Used:

Average Atomic Mass = [ (Atomic Mass of ⁶³X * Natural Abundance of ⁶³X) + (Atomic Mass of ⁶⁵X * Natural Abundance of ⁶⁵X) ] : 100

Putting values,

Average Atomic Mass = [ (62.9296 * 69.15) + (64.9278 * 30.85) ] : 100

Average Atomic Mass = [ (4351.5818) + (2003.0226) ] : 100

Average Atomic Mass = 6354.6044 : 100

Average Atomic Mass = 63.5460 amu