a)Ans: Atomic number of Sodium (Na) – 11Electronic configuration of Sodium – 1s22s22p63s1It has one valence electron, it will lose one electron to get octet configurationAtomic number of Oxygen (O) – 8Electronic configuration of Oxygen – 1s22s22p4It is two electrons short of octet configuration, thus it will gain two electrons.During the bond formation between Sodium and Oxygen, two Sodium atoms loses one electron each to Oxygen atom.2 Na -2e-→ 2Na+O + 2e-→ O-22Na++ O-2→ Na2OAtomic number of Magnesium (Mg) – 12Electronic configuration of Magnesium – 1s22s22p63s2It has two valence electrons, it will lose two electrons to get octet configurationAtomic number of Oxygen (O) – 8Electronic configuration of Oxygen – 1s22s22p4It is two electrons short of octet configuration, thus it will gain two electrons.During the bond formation between Magnesium and Oxygen, one Magnesium atom loses two electrons to Oxygen atom.Mg -1e-→ Mg2+O + 2e-→ O-2Mg+2+ O-2→ MgO

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