Draw plausible Lewis structures for (a) dimethylhydrazine, \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NNH}_{2}\) (b) nitryl chloride, \(\mathrm{ClNO}_{2}\) (Central atom is \(\mathrm{N}\) ) (c) phosphorous acid, a diprotic acid with the empirical formula \(\mathrm{H}_{3} \mathrm{PO}_{3}\).

In \((\mathrm{CH}_{3})_{2} \mathrm{NNH}_{2}\), nitrogen is the central atom. Each Carbon atom has 4 valence electrons, each Hydrogen atom has 1 and each Nitrogen atom has 5. Hence, total valence electrons are \(2*4 + (4+4+3)*1 + 2*5 = 18\).\n\n In \(\mathrm{ClNO}_{2}\), Nitrogen is the central atom. Each Oxygen atom has 6, Chlorine atom has 7 and Nitrogen atom has 5. Hence, total valence electrons are \(2*6 + 7 + 5 = 24\).\n\n In \(\mathrm{H}_{3} \mathrm{PO}_{3}\), Phosphorus is the central atom. Each Hydrogen atom has 1, each Oxygen atom has 6 and the Phosphorus atom has 5. Hence, total valence electrons are \(3*1 + 3*6 + 5 = 24\).

For \((\mathrm{CH}_{3})_{2} \mathrm{NNH}_{2}\), Place the Nitrogen atoms in the center surrounded by Carbon atoms and Hydrogen atoms. Distribute electrons so that each Carbon and Nitrogen atom gets 8 electrons and each Hydrogen atom gets 2 electrons.\n\n For \(\mathrm{ClNO}_{2}\), Place the Nitrogen atom at the center surrounded by one Chlorine atom and two Oxygen atoms. Allocate the electrons so each Oxygen and Chlorine atom gets 8 electrons and Nitrogen atom gets 8 electrons.\n\n For \(\mathrm{H}_{3} \mathrm{PO}_{3}\), place the Phosphorus atom in the center surrounded by three Hydrogen atoms and three Oxygen atoms. Distribute electrons so each Oxygen atom gets 8 electrons, Phosphorus atom gets 8 electrons and each Hydrogen atom gets 2 electrons.

Check that all atoms in each molecule follow the octet rule (2 for Hydrogen atoms), except where exceptions occur. If all atoms in a molecule satisfy the octet rule, the Lewis structure is correctly drawn.