Chapter 1 | Chemical Reactions and Equations Class 10 | NCERT In-text Solutions Explained Simply
Chemical Reactions and Equations Class 10 | NCERT In-text Solutions Explained Simply
Understanding chemical reactions helps us explore how substances interact and transform into new compounds. Below are the simplified and meaningful NCERT in-text question answers from Chapter 1 – Chemical Reactions and Equations (Class 10 Science). These are ideal for quick revision and exam preparation.
📘 Page 6 – NCERT In-text Questions
Q1. Why should a magnesium ribbon be cleaned before burning in the air?
Answer:
Magnesium ribbon is cleaned before burning to remove the thin oxide layer (magnesium oxide) formed on its surface. Cleaning ensures pure magnesium reacts with oxygen, producing a bright white flame and an accurate reaction.
Q2. Write the balanced equation for the following chemical reactions.
(i) Hydrogen + Chlorine → Hydrogen Chloride
👉 Balanced Equation: H₂ + Cl₂ → 2HCl
(ii) Barium Chloride + Aluminium Sulphate → Barium Sulphate + Aluminium Chloride
👉 Balanced Equation: 3BaCl₂ + Al₂(SO₄)₃ → 3BaSO₄ + 2AlCl₃
(iii) Sodium + Water → Sodium Hydroxide + Hydrogen
👉 Balanced Equation:2Na + 2H₂O → 2NaOH + H₂
Q3. Write a balanced chemical equation with state symbols.
(i) Barium chloride + Sodium sulphate → Barium sulphate + Sodium chloride
👉 Equation: BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)
(ii) Sodium hydroxide + Hydrochloric acid → Sodium chloride + Water
👉 Equation: NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l)
📘 Page 10 – NCERT In-text Questions
Q1. A solution of a substance ‘X’ is used for whitewashing.
(i) Name the substance ‘X’ and write its formula.
👉 Answer: Substance ‘X’ is Calcium Oxide (Quicklime).
Formula: CaO
(ii) Write the reaction of substance ‘X’ with water.
👉 Equation: CaO(s) + H₂O(l) → Ca(OH)₂(aq)
(Calcium hydroxide or slaked lime) is formed, which is used for whitewashing walls.
Q2. Why is the amount of gas collected in one of the test tubes in Activity 1.7 double that in the other? Name this gas.
Answer:
The volume of hydrogen gas collected is double that of oxygen because each water molecule (H₂O) contains two hydrogen atoms and one oxygen atom.
👉 Gas formed in larger amounts: Hydrogen (H₂)
📘 Page 13 – NCERT In-text Questions
Q1. Why does the colour of the copper sulphate solution change when an iron nail is dipped in it?
Answer:
When an iron nail is dipped in copper sulphate solution, iron displaces copper because it is more reactive than copper.
👉 Equation: Fe + CuSO₄ → FeSO₄ + Cu
The blue colour fades, and a reddish-brown deposit of copper appears on the nail.
Q2. Give an example of a double displacement reaction other than the one given in Activity 1.10.
Answer:
👉 Example:
Na₂CO₃ + CaCl₂ → 2NaCl + CaCO₃↓
Here, calcium carbonate (CaCO₃) forms as a white precipitate.
Q3. Identify the substances oxidised and reduced in the following reactions.
(i) 4Na(s) + O₂(g) → 2Na₂O(s)
👉 Sodium (Na) is oxidised to Na₂O.
👉 Oxygen (O₂) is reduced to oxide ions (O²⁻).
(ii) CuO(s) + H₂(g) → Cu(s) + H₂O(l)
👉 Hydrogen (H₂) is oxidized to H₂O.
👉 Copper(II) oxide (CuO) is reduced to copper (Cu).
🌟 Conclusion
Chemical reactions occur all around us — from the rusting of iron to the burning of fuel. Understanding how to balance chemical equations and identify reaction types lays the foundation for a deeper understanding of chemistry concepts.
These short, crisp NCERT in-text solutions make learning simple, effective, and exam-ready for every Class 10 student.
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