Question

practice questions-physical and chemical properties

1. identify each of the following properties as either chemical(c) or physical (p)

burning wood	chemical change
melting point of water is 0°	physical change
the color of the book is red	physical change
rusting of a nail	chemical change
forcing a piece of metal into a sheet	physical change
stretching of a metal into a wire
density of water is 1 g/cm³	physical change
rising of dough when placed in an oven	chemical change
dissolving of sugar in water	physical change

Answer:

To determine if the given answers are correct, we analyze each property:

1. Burning wood

• Explanation: Burning wood involves a chemical reaction (combustion) producing new substances (ash, CO₂, etc.).
• Correctness: Labeled as "Chemical Change" – Correct (should be "Chemical (C)" for property, but the concept of chemical change here aligns; the term "change" vs "property" is a minor wording issue, but the classification is right).

2. Melting point of water is \( 0^\circ \)

• Explanation: Melting point is a physical property (describes state change without new substances).
• Correctness: Labeled as "Physical Change" – Incorrect (melting point is a physical property, not a change. The answer confuses "property" with "change," but the classification as "physical" (vs chemical) is conceptually right, though the term "change" is inaccurate).

3. The color of the book is red

• Explanation: Color is a physical property (no chemical reaction, describes appearance).
• Correctness: Labeled as "Physical Change" – Incorrect (color is a physical property, not a change. Again, wording issue, but classification as "physical" is conceptually right).

4. Rusting of a nail

• Explanation: Rusting is a chemical reaction (iron + oxygen + water → rust, new substance).
• Correctness: Labeled as "Chemical change" – Correct (rusting is a chemical change, so the classification is right, even with "change" vs "property" wording).

5. Forcing a piece of metal into a sheet

• Explanation: This is shaping (malleability), a physical change (no new substance, just form).
• Correctness: Labeled as "Physical change" – Correct (malleability is a physical property, and shaping is a physical change; classification is right).

6. Stretching of a metal into a wire

• Explanation: This is ductility (physical property), a physical change (no new substance, just form).
• Correctness: No label (blank) – Incorrect (should be "Physical (P)" or "Physical Change").

7. Density of water is \( 1 \, \text{g/cm}^3 \)

• Explanation: Density is a physical property (describes mass/volume, no chemical reaction).
• Correctness: Labeled as "Physical Change" – Incorrect (density is a physical property, not a change. Wording issue, but classification as "physical" is conceptually right).

8. Rising of dough when placed in an oven

• Explanation: Dough rising involves yeast fermentation (chemical reaction, new gases/substances).
• Correctness: Labeled as "Chemical Change" – Correct (fermentation is a chemical change, classification is right).

9. Dissolving of sugar in water

• Explanation: Dissolving sugar is a physical change (sugar disperses, no new substance; can be reversed).
• Correctness: Labeled as "Physical Change" – Correct (dissolving is a physical change, classification is right).

Summary of Corrections:

• For properties 2, 3, 7: The term "change" is incorrect (they are properties, not changes), but the "physical" classification is conceptually right.
• Property 6: Missing label (should be "Physical Change" or "Physical (P)").

If we strictly distinguish "property" (describes a substance) from "change" (process), the answers have wording errors but mostly correct classifications. For example:

• "Melting point of water is \( 0^\circ \)" is a physical property (P), not a "change."
• "The color of the book is red" is a physical property (P), not a "change."
• "Density of water is \( 1 \, \text{g/cm}^3 \)" is a physical property (P), not a "change."
• "Stretching of a metal into a wire" is a physical change (P) (or property: ductility).

To reclassify correctly (using "C" for chemical property/change, "P" for physical):

Property/Process	Correct Classification (C/P)	Given Label (Correct? Y/N)
Melting point of water is \( 0^\circ \)	P (property)	N (labeled as "Change")
The color of the book is red	P (property)	N (labeled as "Change")
Rusting of a nail	C	Y (Chemical Change)
Forcing a metal into a sheet	P (change/property)	Y (Physical Change)
Stretching metal into a wire	P (change/property)	N (blank)
Density of water is \( 1 \, \text{g/cm}^3 \)	P (property)	N (labeled as "Change")
Rising of dough in oven	C	Y (Chemical Change)
Dissolving sugar in water	P (change)	Y (Physical Change)

The core classifications (physical vs chemical) are mostly correct, but the term "change" is misused for "properties" (melting point, color, density are properties, not changes).