Which of these elements has two valence electrons? a. hydrogen (h) b. barium (ba) c. nitrogen (n) d. krypton (kr) e. bromine (br)

So whenever you need to find valence electron look at Group Number and you can find it, Example barium it’s on group 2 it’s means it have 2 valence electrons.
let’s look for nitrogen group 5A that means it have 5 valence eletrons.
hope it’s help.
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The answer is b i think