Final answer:
The substance cannot be table salt because table salt is known to dissolve in water, whereas the substance in question does not; thus, its properties do not match those of sodium chloride.
Step-by-step explanation:
No, the white powdery substance that does not dissolve in water but does form a solution in oil cannot be table salt because ordinary table salt, which is sodium chloride, is known to easily dissolve in water. This is a characteristic property of table salt, and it helps to differentiate between this substance and other white powdery substances. As such, if the substance in question does not dissolve in water, it is likely that it is not table salt.
You can conduct a simple experiment to test for the presence of chloride by preparing a solution of the unknown salt using distilled water and adding a small amount of silver nitrate solution. A white precipitate indicates the presence of a chloride, which could suggest that the powder is a salt different from sodium chloride if it does not dissolve in water. However, the lack of water solubility already suggests it is not table salt.