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NCERT Class 10 Science Chemical Reactions and Equations: In-text questions (page 6) Solutions
AI-written, checked on 23 Oct 2026
Solutions written by Shishya, checked — not the board's official answers
Step-by-step working for every question of In-text questions (page 6) in NCERT's Class 10 Science book, chapter “Chemical Reactions and Equations”, written by Shishya. Each question is in our own short words; open the NCERT chapter for the exact wording and figures.
How these were checked: the solutions were drafted with AI and then read and corrected on 23 Oct 2026. Every numerical final answer is recomputed from the question's own numbers by a calculator check that runs before each release; proofs and explanations were read, not machine-checked. The NCERT textbook is the authority — if something here disagrees with it, follow the book.
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In-text (page 6) Q1
Why should a magnesium ribbon be cleaned before burning it in air?
- Magnesium is a highly reactive metal that reacts with oxygen in the air.
- This reaction forms a layer of magnesium oxide on the surface of the ribbon.
- The magnesium oxide layer is non-combustible and acts as a barrier.
- This barrier prevents the inner magnesium from reacting with oxygen.
- Cleaning the ribbon removes this oxide layer to allow the metal to burn properly.
Answer: The magnesium ribbon should be cleaned to remove the layer of magnesium oxide that prevents the metal from reacting with oxygen.
In-text (page 6) Q2
Write balanced equations: (i) hydrogen + chlorine → hydrogen chloride (ii) barium chloride + aluminium sulphate → barium sulphate + aluminium chloride (iii) sodium + water → sodium hydroxide + hydrogen.
- (i) Write the unbalanced equation: H₂ + Cl₂ → HCl
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (i) Balance the hydrogen and chlorine atoms by placing a coefficient of 2 before HCl: H₂ + Cl₂ → 2HCl
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (ii) Write the unbalanced equation: BaCl₂ + Al₂(SO₄)₃ → BaSO₄ + AlCl₃
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (ii) Balance the barium and sulphate groups by placing a coefficient of 3 before BaCl₂ and BaSO₄: 3BaCl₂ + Al₂(SO₄)₃ → 3BaSO₄ + AlCl₃
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (ii) Balance the aluminium and chlorine atoms by placing a coefficient of 2 before AlCl₃: 3BaCl₂ + Al₂(SO₄)₃ → 3BaSO₄ + 2AlCl₃
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (iii) Write the unbalanced equation: Na + H₂O → NaOH + H₂
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (iii) Balance the hydrogen atoms by placing a coefficient of 2 before H₂O and NaOH: Na + 2H₂O → 2NaOH + H₂
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (iii) Balance the sodium atoms by placing a coefficient of 2 before Na: 2Na + 2H₂O → 2NaOH + H₂
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
Answer: (i) H2 + Cl2 → 2HCl; (ii) 3BaCl2 + Al2(SO4)3 → 3BaSO4 + 2AlCl3; (iii) 2Na + 2H2O → 2NaOH + H2
- (i) Write the unbalanced equation: H₂ + Cl₂ → HCl
In-text (page 6) Q3
Write balanced equations with state symbols: (i) barium chloride and sodium sulphate solutions give insoluble barium sulphate and sodium chloride solution (ii) sodium hydroxide solution reacts with hydrochloric acid solution to give sodium chloride solution and water.
- (i) Identify the reactants as barium chloride and sodium sulphate, both in aqueous solution.
- (i) Identify the products as insoluble barium sulphate (solid) and sodium chloride (aqueous).
- (i) Write the unbalanced equation: BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + NaCl(aq).
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (i) Balance the chlorine and sodium atoms by placing a coefficient of 2 before NaCl.
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (i) The final balanced equation is BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq).
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (ii) Identify the reactants as sodium hydroxide and hydrochloric acid, both in aqueous solution.
- (ii) Identify the products as sodium chloride (aqueous) and water (liquid).
- (ii) Write the equation: NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l).
- (ii) Check the atom count; all elements are already balanced with a 1:1:1:1 ratio.
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
- (ii) The final balanced equation is NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l).
why?
A balanced equation has the same number of atoms of each element on both sides, because atoms are neither created nor destroyed in a chemical reaction (law of conservation of mass). Only the numbers in front (coefficients) change, never the formulas.
Answer: (i) BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq); (ii) NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
Other exercises in this chapter
- In-text questions (page 10) — 2 questions
- In-text questions (page 13) — 3 questions
- End-of-chapter exercises — 20 questions
← Chemical Reactions and Equations: notes, practice and all exercises
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