In the statements provided, we can identify different types of properties as follows:
(a) Yellow-green chlorine gas attacks silvery sodium metal to form white crystals of sodium chloride.
- Physical Properties: The colors of chlorine gas (yellow-green) and sodium metal (silvery), as well as the appearance of the product (white crystals of sodium chloride), are physical properties.
- Chemical Properties: The interaction between chlorine gas and sodium metal (the reaction that forms sodium chloride) represents a chemical property.
(b) A magnet separates a mixture of black iron shavings and white sand.
- Physical Properties: The colors of the materials (black iron shavings and white sand) and their magnetic properties (iron is magnetic while sand is not) are physical properties.
- Separation Technique: The use of a magnet to separate the mixture is based on the physical property of magnetism.
In summary, both statements involve identification of physical properties (color, appearance) and, in the first statement, chemical properties (reactivity). The second statement involves physical properties used in a physical separation method.