Three different atoms or atomic cations with 4 electrons

Explanation:Since Li has an atomic number of 3, this tells us that it has 3 electrons and 3 protons

Be has atomic number of 4, so in ground state, it will have 4 electrons and 4 protons. + 1 charge indicates of loss of 1 electron. Therefore Be with 3 electrons is Be+

Same with B which has atomic number of 5. So + 2 charge indicates loss of 2 electrons.