which of the following is not an example of a chemical change?\na formation of red colored rust on an iron…

which of the following is not an example of a chemical change?\na formation of red colored rust on an iron nail\nb formation of a green coating on a copper coin\nc formation of a pink solution on dissolving pink colored flavored drink mix in water\nd formation of a pink liquid when a drop of colorless phenolphthalein solution is added to colorless sodium hydroxide solution

which of the following is not an example of a chemical change?\na formation of red colored rust on an iron nail\nb formation of a green coating on a copper coin\nc formation of a pink solution on dissolving pink colored flavored drink mix in water\nd formation of a pink liquid when a drop of colorless phenolphthalein solution is added to colorless sodium hydroxide solution

Answer

Brief Explanations:

  • Option A: Rust formation on an iron nail is a chemical change. Iron reacts with oxygen and moisture to form iron oxide (rust), a new substance.
  • Option B: The green coating on a copper coin is a chemical change. Copper reacts with substances like carbon dioxide and water in the air to form copper carbonate (the green - colored compound), a new substance.
  • Option C: Dissolving a pink - colored flavored drink mix in water is a physical change. It is a process of dispersion of the drink mix particles in water. There is no new chemical substance formed. The drink mix can be recovered by evaporation of water.
  • Option D: When phenolphthalein is added to sodium hydroxide, a chemical reaction occurs. Phenolphthalein is an acid - base indicator. In a basic medium (sodium hydroxide is a strong base), it changes its structure and shows a pink color. A new chemical species (the colored form of phenolphthalein in basic medium) is formed.

Answer:

C. Formation of a pink solution on dissolving pink colored flavored drink mix in water