The ability of a substance to float or sink in a liquid depends on its density, which is the mass of the substance per unit of volume. If the density of a substance is greater than the density of the liquid it is placed in, it will sink. If the density of a substance is less than the density of the liquid it is placed in, it will float.

Lemons and limes are both citrus fruits that are similar in size and shape, but they have some differences in their composition that can affect their densities. One reason why a lemon may float in water while a lime sinks is due to their relative sizes. Lemons are generally larger and have a thicker skin compared to limes, which may make them less dense and more likely to float.

Another reason why a lemon may float in water while a lime sinks is due to their relative acidities. Lemons are generally more acidic than limes, which can affect their densities. The acidity of a substance can cause it to release gases, which can cause it to become less dense and more likely to float.

A third reason why a lemon may float in water while a lime sinks is due to their relative sugar content. Lemons are generally less sweet than limes, which may affect their densities. The sugar content of a substance can cause it to dissolve in water, which can affect its density and its ability to float or sink.

Overall, the ability of a lemon or a lime to float or sink in water depends on several factors, including their size, acidity, and sugar content. These factors can affect the densities of the fruits and determine whether they float or sink in water.