Class 7 Science Chapter 5 Changes Around Us Physical and Chemical Solutions | Curiosity NCERT Answers 2026-27 | Amresh Academy

Class 7 Science Chapter 5 Changes Around Us Physical and Chemical Solutions | Curiosity NCERT Answers 2026-27 | Amresh Academy

NS 7TH C E
Published on By Amresh Academy

  


 

ЁЯМЯ Class 7 Science Curiosity – Chapter 5 Solutions

ЁЯФе Changes Around Us: Physical and Chemical | Amresh Academy

ЁЯУЭ ЁЯФ╣ Let Us Enhance Our Learning

1. Which of the following statements are the characteristics of a physical change?

(i) The state of the substance may or may not change.
(ii) A substance with different properties is formed.
(iii) No new substance is formed.
(iv) The substance undergoes a chemical reaction.
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iii)
(d) (iii) and (iv)

ЁЯСЙ Answer: (c) (i) and (iii) ✅

ЁЯСЙ Explanation:
✔️ Physical change → only form/state changes
❌ No new substance is formed

2. Predict which of the following changes can be reversed and which cannot be reversed. If you are not sure, you may write that down. Why are you not sure about these?

(i) Stitching cloth to a shirt
(ii) Twisting of straight string
(iii) Making idlis from a batter
(iv) Dissolving sugar in water
(v) Drawing water from a well
(vi) Ripening of fruits
(vii) Boiling water in an open pan
(viii) Rolling up a mat
(ix) Grinding wheat grains to flour
(x) Forming of soil from rocks

ЁЯСЙ Answer:

(i) Cannot be reversed ❌
(ii) Can be reversed ЁЯФД
(iii) Cannot be reversed ❌
(iv) Can be reversed ЁЯФД
(v) Can be reversed ЁЯФД
(vi) Cannot be reversed ❌
(vii) Can be reversed ЁЯФД
(viii) Can be reversed ЁЯФД
(ix) Cannot be reversed ❌
(x) Cannot be reversed ❌

3. State whether the following statements are True or False. In case a statement is False, write the correct statement.

(i) Melting of wax is necessary for burning a candle. (True/False)
(ii) Collecting water vapour by condensing involves a chemical change. (True/False)
(iii) The process of converting leaves into compost is a chemical change. (True/False)
(iv) Mixing baking soda with lemon juice is a chemical change. (True/False)

ЁЯСЙ Answer:

(i) True ✅
(ii) False ❌ → It is a physical change
(iii) True ✅
(iv) True ✅

4. Fill in the blanks in the following statements:

(i) Nalini observed that the handle of her cycle has got brown deposits. The brown deposits are due to ______ and this is a ______ change.
(ii) Folding a handkerchief is a ______ change and can be ______.
(iii) A chemical process in which a substance reacts with oxygen with evolution of heat is called ______ and this is a ______ change.
(iv) Magnesium, when burnt in air, produces a substance called ______. The substance formed is ______ in nature. Burning of magnesium is a ______ change.

ЁЯСЙ Answer:

(i) rusting, chemical
(ii) physical, reversed
(iii) combustion, chemical
(iv) magnesium oxide, basic, chemical

5. Are the changes of water to ice and water to steam, physical or chemical? Explain.

ЁЯСЙ Answer:
These are physical changes ЁЯФД

ЁЯСЙ Explanation:
Only state changes (solid/liquid/gas)
✔️ Substance remains same → H₂O

6. Is curdling of milk a physical or chemical change? Justify your statement.

ЁЯСЙ Answer:
It is a chemical change ЁЯзк

ЁЯСЙ New substance (curd) forms → irreversible

7. Natural factors, such as wind, rain, etc., help in the formation of soil from rocks. Is this change physical or chemical and why?

ЁЯСЙ Answer:
✔️ Both physical + chemical

ЁЯСЙ Physical → breaking rocks
ЁЯСЙ Chemical → reactions with air/water

8. Read the following story titled ‘Eco-friendly Prithvi’...

ЁЯСЙ Answer:

  • Cutting vegetables → physical change
  • Collecting waste → physical change
  • Decomposition → chemical change
  • Plant growth → chemical change

ЁЯСЙ Title: ЁЯМ▒ “Waste to Wealth”

9. Some changes are given here... (Venn Diagram)

ЁЯСЙ Answer:

ЁЯФ╡ A (Physical):

  • Tearing paper
  • Melting ice
  • Folding clothes

ЁЯФ┤ B (Chemical):

  • Rusting
  • Curdling milk
  • Ripening fruits
  • Burning magnesium
  • Baking soda + vinegar

ЁЯЯг C (Both):

  • Burning candle ЁЯХп️

10. The experiments shown in Fig. 5.11a, b, c and d were performed. Find out in which case(s) did lime water turn milky and why?

(a) Vinegar and baking soda
(b) Lemon juice and vinegar
(c) Vinegar and common salt
(d) Lemon juice and baking soda

ЁЯСЙ Answer: (a) and (d) ✅

ЁЯСЙ Reason:
Carbon dioxide gas is formed → turns lime water milky ЁЯзк

✍️ ЁЯФ╣ Very Short Answer Type Questions

What is a physical change?

ЁЯСЙ No new substance formed ЁЯФД

What is a chemical change?

ЁЯСЙ New substance formed ЁЯзк

Give one example of a reversible change.

ЁЯСЙ Melting ice ❄️

Which gas turns lime water milky?

ЁЯСЙ Carbon dioxide ЁЯТи

What is ignition temperature?

ЁЯСЙ Minimum temp to start burning ЁЯФе

ЁЯза ЁЯФ╣ Short Answer Type Questions

How is a physical change different from a chemical change?

ЁЯСЙ Physical → no new substance
ЁЯСЙ Chemical → new substance formed

Why is rusting of iron considered a chemical change?

ЁЯСЙ Forms new substance (iron oxide) ЁЯЯд

What is combustion?

ЁЯСЙ Reaction with oxygen + heat ЁЯФе

How does burning of a candle involve both physical and chemical changes?

ЁЯСЙ Melting → physical
ЁЯСЙ Burning → chemical

What is the role of oxygen in combustion?

ЁЯСЙ Supports burning ЁЯМм️

ЁЯУЦ ЁЯФ╣ Descriptive Answer Type Questions

What are the three essential conditions for combustion?

ЁЯСЙ Fuel + Oxygen + Heat ЁЯФе

Describe what happens when vinegar reacts with baking soda.

ЁЯСЙ Produces CO₂ gas → chemical change

Why is burning of magnesium a chemical change?

ЁЯСЙ New substance (MgO) formed

How do both physical and chemical changes occur in a burning candle?

ЁЯСЙ Wax melts + burns simultaneously

What is weathering of rocks?

ЁЯСЙ Breaking of rocks → soil formation ЁЯМН

ЁЯЪА ЁЯФ╣ Exploring Questions

Why are some changes considered undesirable?

ЁЯСЙ Cause damage (rusting, spoilage)

Can chemical changes be prevented? Explain with an example.

ЁЯСЙ Yes → painting, oiling prevents rust

Why is burning paper using sunlight a chemical change?

ЁЯСЙ New substances (ash, gas) formed

Is curdling of milk a physical or chemical change? Justify.

ЁЯСЙ Chemical change ЁЯзк

How does erosion represent a physical change?

ЁЯСЙ Only form changes, no new substance

 

Label :
Amresh Academy

0 comments:

Subscribe to: Post Comments (Atom)