Question

which of the following is an example of the formation of a mixture?
rust forming on an iron nail.
sugar crystals dissolving in water.
hydrogen and oxygen reacting to produce oxygen.
sodium and chlorine forming table salt.

Explanation:

A mixture is formed when two or more substances are combined without forming a new substance. Let's analyze each option:

• Rust forming on an iron nail: This is a chemical reaction (oxidation) where iron reacts with oxygen and moisture to form rust (a new substance), so it's a chemical change, not a mixture formation.
• Sugar crystals dissolving in water: When sugar dissolves in water, the sugar molecules are dispersed in the water, and no new substance is formed. The resulting mixture is a solution (a type of mixture) of sugar and water.
• Hydrogen and oxygen reacting to produce oxygen: Wait, hydrogen and oxygen react to form water (not oxygen). This is a chemical reaction forming a new substance (water), so it's a chemical change, not a mixture.
• Sodium and chlorine forming table salt: Sodium and chlorine react chemically to form sodium chloride (table salt), a new substance, so it's a chemical change, not a mixture.

So the correct option is the one with "Sugar crystals dissolving in water".

Answer:

The option with "Sugar crystals dissolving in water" (the blue - colored option with the text "Sugar crystals dissolving in water")