Final answer:
In an undercooked meringue, the sugar is most likely to crystallize rather than caramelize or turn into syrup. Heating sugar over a high flame can lead to caramelization followed by charring, resulting in a carbon-dominated mixture. Sugar cubes stored at room temperature in a water dish on a table will remain unchanged.
Step-by-step explanation:
When an undercooked meringue is considered, the sugar in it will most likely crystallize. Undercooking a meringue means that the sugar has not been fully dissolved nor given enough heat to caramelize or turn into syrup. If the temperature is insufficient for these reactions to happen, the sugary liquid may retreat back into crystals as it cools down. However, the sugar will not remain entirely unchanged due to the partial cooking process it has undergone.
If you heat sugar with a high flame, as in placing table sugar in a spoon over it, the sugar can undergo caramelization at first, and then if the temperature keeps rising, it can char and become a blackened mixture, which is primarily composed of carbon. This process is a chemical reaction, where sugar molecules decompose under the influence of intense heat. The chemical equation for caramelization, although complex and not easily represented by a simple equation, involves the thermal decomposition of sugar, resulting in various compounds, including carbon.
Based on these understandings, sugar cubes in a bowl placed in a dish of water can be stored on a table without worry of them undergoing such reactions, because there is no high heat source to trigger caramelization or charring. They will remain unchanged in normal room conditions.