Question

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Answer 1

Check the location of Lithium on the periodic table and note its atomic number.

Answer 2

For lithium? No. It's usual atomic weight is 6, but its atomic number (the number of protons in its nucleus) is 3.

Answer 3

So now you should be able to calculate the neutrons. 6-3 = 3 neutrons.

Answer 4

@wincenty not if the isotope had an atomic weight of 9.
See http://openstudy.com/study#/updates/5081ca25e4b0dab2a5ebab8e