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.
Carbon dioxide, or #CO_2#, has three resonance structures, out of which one is a major contributor. The #CO_2# molecule has a total of 16 valence electrons - 4 from carbon and 6 from each oxygen atom. Here are the three resonance structures for #CO_2#, all accounting for the 16 valence electrons. The atoms in all three resonance structures have full octets; however, structure 1 will be more stable, and thus contribute more, because it has no separation of charge.