I'll work through each question step by step to find the correct answers.
Question 1: Which change can be easily reversed?
Let me think about this:
- Physical changes are changes in appearance or state (like melting ice, tearing paper) - these can usually be reversed
- Chemical changes create new substances (like burning wood, rusting iron) - these cannot be easily reversed
- So physical changes are the ones that can be easily reversed
Answer:
(B) Physical Change
Question 2: If the chemical properties of a substance remain unchanged and the appearance or shape of a substance changes, it is called a...
Breaking this down:
- Chemical properties unchanged = no new substance formed
- Only appearance/shape changed = just physical characteristics altered
- This describes a physical change perfectly
Answer:
(A) Physical change
Question 3: Which of the following characteristic best describes a physical change?
Let me check each option:
- (A) Composition changes - No, that's chemical change
- (B) Composition remains the same - Yes! In physical changes, the substance stays the same
- (C) State of the matter remains same - Not always true (ice melting to water is physical but state changes)
- (D) Loss of mass - No, mass is conserved in both types of changes
Answer:
(B) Composition remains the same
Question 4: Which of the following property remains same during physical as well as chemical changes?
Checking each option:
- (A) Density - Can change in both types
- (B) Shape - Changes in physical changes
- (C) Mass - YES! Mass is conserved in ALL changes (law of conservation of mass)
- (D) Arrangement of particle - Changes in both types
Answer:
(C) Mass
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Final Answer:
(1) B
(2) A
(3) B
(4) C
Parent Tip: Review the logic above to help your child master the concept of 7th grade chemistry worksheet.
