The most commonly used diagnostic tool for tuberculosis is a simple skin test, though blood tests are becoming more commonplace. A small amount of a substance called PPD tuberculin is injected just below the skin of your inside forearm. You should feel only a slight needle prick.
The structure has a double bond and an adjacent atom with a lone pair, so it could have resonance. The possible resonance structures are below. The first structure has the most common bonding pattern for all of its atoms, so it is a reasonable Lewis structure.
Lewis structure. Lewis structures (also known as Lewis dot diagrams, electron dot diagrams, and electron dot structures) are diagrams that show the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule. A Lewis structure can be drawn for any covalently bonded molecule, as well as coordination compounds.