Difficulty: Easy
Correct Answer: All of the above
Explanation:
Introduction / Context:
Chemistry distinguishes between physical changes and chemical changes. A physical change affects the form, state, or appearance of a substance without creating a new substance, while a chemical change produces one or more new substances with different properties. Recognizing this difference is a fundamental skill in science. This question asks you to identify which listed processes are examples of physical change, using common experiences such as dissolving sugar, breaking glass, and melting ice.
Given Data / Assumptions:
Concept / Approach:
In a physical change, the particles of the substance remain the same, but their arrangement, spacing, or state may change. For example, ice and liquid water are both H2O, so melting ice is a change of state but not of chemical composition. Dissolving sugar in water disperses sugar molecules among water molecules, but the sugar remains chemically sugar and can be recovered by evaporation. Breaking glass changes the shape and size of the glass pieces, but the material remains the same glass substance. Since no new substances are formed in any of these processes, each one qualifies as a physical change. When a question offers several correct examples and then an option like all of the above, that combined option is the best choice.
Step-by-Step Solution:
1. Consider dissolving sugar in water. The sugar crystals disappear visually, but the sugar molecules are still present in the solution and can be recovered, so this is a physical change.2. For breaking glass, the object shatters into smaller pieces, but the chemical composition and properties of the glass itself do not change. This is also a physical change.3. When ice melts, solid water changes to liquid water. Both forms have the same chemical formula, H2O, which indicates a change of state rather than a chemical reaction.4. In none of these processes does a new substance with new chemical properties appear.5. Therefore, all three examples meet the definition of a physical change.6. The answer that gathers all correct examples is the option all of the above.
Verification / Alternative check:
Another way to check is to ask whether the changes are easily reversible by simple physical methods. Sugar can be recovered from sugar solution by evaporating the water. Broken glass pieces can be melted and reshaped, though not in everyday life, which shows that no new substance was formed. Ice can be refrozen to return to its original state. In each case, the possibility of reversal without chemical reaction supports the idea that these are physical changes. By contrast, burning paper or rusting iron produce new substances and cannot be reversed by simple physical methods, which is why they are classified as chemical changes.
Why Other Options Are Wrong:
Option A alone, dissolving sugar in water, is a correct example but does not capture the fact that the other listed processes are also physical changes. Option B alone, breaking glass, is also correct but incomplete. Option C alone, melting ice, is again a correct but incomplete example. The question allows you to recognize that more than one option describes a physical change and therefore the multiple correct examples should be chosen together using all of the above.
Common Pitfalls:
Students sometimes assume that a dramatic change in appearance, such as breaking glass, must mean a chemical change, but this is not true if the substance itself remains the same. Another pitfall is to confuse dissolving with chemical reaction because the solid seems to vanish. In reality, dissolving is often just a physical mixing at the molecular level. To avoid confusion, always ask whether the chemical identity of the substance changes and whether you could, in principle, recover the original material by physical means.
Final Answer:
Dissolving sugar in water, breaking glass, and melting ice are all examples of physical change, so the correct choice is All of the above.
Discussion & Comments