Answer :
The percentage abundance of lithium 6 is 6% and percentage abundance of lithium 7 is 94%.
Relative atomic mass is defined as the ratio of the average mass of atoms of a chemical element in a given sample to the atomic mass constant. The atomic mass constant is defined as being 1/12 of the mass of a carbon-12 atom.
R.A.M = (Mass.no ×Abundance) / (Total abundance)
Let the abundance of Li-6 be x
Relative abundance of Li-7 will be 100−x.
6.94 = (6 × x)+ 7(100−x) / 100
6x + 700 – 7x = 694
X = 6%
Li-6 has 6%, Li-7 has 94% because the sum of the percent natural abundances of all the isotopes of any given element must total 100%. atoms that have the same atomic number (number of protons), but different mass numbers that is number of protons and neutrons are called isotopes.
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