Two stable isotopes of lithium `._3^6Li` and `._3^7Li` have respective abundances of 7.5% and 92.5% . These isotopes have masses 6.0152 u and 7.016004 u respectively. Find the atomic weight of lithium

Options

A. 6.941 u
B. 3.321 u
C. 2.561 u
D. 0.621 u

Answer

a

Explanation

Atomic weight = average weight of the isotopes
`=(6.01512xx7.5xx7.01600xx92.5)/((7.5+92.5))=(45.1134+648.98)/100`
=6.941 u