Final answer:
The property to distinguishes talc from gypsum is hardness, with talc having a Mohs hardness of 1 and gypsum a hardness of 2.
Step-by-step explanation:
One key property that can be used to distinguish talc from gypsum is hardness. Hardness is a measure of a mineral's resistance to scratching, and it is often quantified using the Mohs scale of mineral hardness.
Talc, composed of magnesium, silicon, and oxygen, is the softest mineral on the Mohs scale, assigned a value of 1. It is so soft that it can be easily scratched with a fingernail. Talc is commonly used in the production of talcum powder.
In contrast, gypsum, which consists of calcium, sulfur, and oxygen, has a slightly higher hardness. Gypsum is assigned a value of 2 on the Mohs scale. While still relatively soft, gypsum cannot be scratched by a fingernail but can be scratched by a fingernail. Gypsum is commonly used in the construction industry for making plaster.
By assessing the hardness of a mineral sample using the Mohs scale, one can differentiate talc and gypsum. If the mineral can be scratched by a fingernail, it is likely talc; if it cannot be scratched by a fingernail but can be scratched by a fingernail, it is likely gypsum. This property provides a practical and straightforward method for distinguishing between these two minerals.