Question

when sodium reacts with chlorine, a chemical change occurs forming salt. which of the following pieces of evidence best supports this claim?

○ chlorine is a metal. salt is a nonmetal. metals always gain electrons from nonmetals causing chemical reactions.

○ the atmospheric humidity at which this occurs is constant. if the atmosphere is not humid enough, the change will not occur.

○ the temperature at which this occurs is constant. if the atmosphere is any warmer or colder, the change will not occur.

○ chlorine is a gas at room temperature. salt is a solid. the product of the change has new properties.

Explanation:

1. Analyze Option 1: Chlorine is a non - metal, not a metal, and metals generally lose electrons while non - metals gain electrons. So this option has incorrect information.
2. Analyze Option 2: Atmospheric humidity affecting the reaction does not prove it is a chemical change. A chemical change is about the formation of new substances, not about the effect of humidity on the reaction rate or occurrence.
3. Analyze Option 3: Temperature affecting the reaction also does not prove it is a chemical change. Temperature can affect physical processes too, and this does not relate to the formation of a new substance.
4. Analyze Option 4: Chlorine is a gas (with its own set of properties) and salt is a solid with new properties. The formation of a substance with new properties is a key indicator of a chemical change.

Answer:

D. Chlorine is a gas at room temperature. Salt is a solid. The product of the change has new properties.