Which of the following statements about ice melting is true?

• A. Ice melting is a chemical change because new substances are formed.
• B. Ice melting is a physical change because it involves a change in state without altering the chemical composition of H_2O.
• C. Ice melting is irreversible under normal conditions.
• D. Ice melting results in the formation of hydrogen and oxygen gases.

Answer: (B)

Verified step by step guidance

1. Understand the difference between physical and chemical changes: A physical change affects the form of a substance but not its chemical composition, while a chemical change results in the formation of new substances with different chemical properties.
2. Analyze the process of ice melting: When ice melts, it changes from solid water (ice) to liquid water, but the chemical formula H_2O remains the same throughout the process.
3. Evaluate the statements given: Since no new substances are formed during melting, it is not a chemical change, so the statement claiming it is a chemical change is false.
4. Consider reversibility: Melting ice is generally reversible by freezing the water again, so the statement that melting is irreversible under normal conditions is false.
5. Check for gas formation: Melting ice does not produce hydrogen or oxygen gases; it only changes the physical state from solid to liquid, so that statement is also false.