Chemical Reactions and Equations

Science Class 10 – Chemistry – Chapter 1: Chemical Reactions and Equations

Science Class 10 – Chemistry

Chapter 1: Chemical Reactions and Equations • Interactive Quiz (DHA 01, 02, 03, 05, 06)

DHA 01 — Chemical Reactions and Equations

Covers physical vs chemical changes, indicators of chemical reactions.

Q1. Which of the following is a chemical change?

(A) Twinkling of stars (B) Rusting of iron (C) Cutting of fruits (D) Boiling of water

Hint: Look for formation of a new substance.

Q2. A chemical change may involve —

(A) Change in colour only (B) Change in temperature only (C) Evolution of gas only (D) All of the above

Q3. Which of the following is not a physical change?

(A) Boiling of water to give steam (B) Melting of ice to give water (C) Dissolving sugar in water (D) Combustion of LPG

Q4. Which of the following is/are true when milk changes into curd?

(i) State changes liquid → semi-solid; (ii) Colour changes; (iii) Taste changes; (iv) Irreversible change

(A) (i) and (ii) (B) (ii) and (iii) (C) (i), (iii) and (iv) (D) (i) and (iv)

Q5. Which of the following does not involve a chemical reaction?

(A) Digestion of food (B) Respiration (C) Burning of candle wax (D) Melting of candle wax

DHA 02 — Balancing and Stoichiometry

Focus: conservation of mass and stoichiometric coefficients.

Q1. We balance equations to obey the:

(A) Law of constant proportion (B) Law of conservation of mass (C) Law of multiple proportion (D) Law of reciprocal proportion

Q2. Find the stoichiometric coefficients: aAl + bO₂ → cAl₂O₃

(A) a=3, b=2, c=4 (B) a=2, b=4, c=3 (C) a=4, b=3, c=2 (D) a=2, b=3, c=4

Balanced: 4Al + 3O₂ → 2Al₂O₃.

Q3. Find the stoichiometric coefficients: aH₂S + bO₂ → cH₂O + dSO₂

(A) 2,1,2,3 (B) 2,1,1,3 (C) 3,2,3,2 (D) 2,3,2,2

Balanced: 2H₂S + 3O₂ → 2H₂O + 2SO₂.

Q4. Find the stoichiometric coefficients: aNa₂SO₄ + bBaCl₂ → cBaSO₄ + dNaCl

(A) 1,1,1,1 (B) 2,1,1,2 (C) 1,2,1,2 (D) 1,1,1,2

Balanced: Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl.

DHA 03 — Endothermic/Exothermic, Types of Reactions

Focus: heat exchange, reaction classification, states and coefficients.

Q1. Which of the following is/are endothermic?

(i) Boiling water (ii) Combustion of fuel (iii) Melting wax (iv) Sublimation of dry ice

(A) (i) and (ii) (B) (i) and (iii) (C) (i), (ii) and (iv) (D) (i), (iii) and (iv)

Q2. Which is not an exothermic reaction?

(A) Burning of natural gas (B) Photosynthesis (C) Respiration (D) Composting

Q3. Identify the variables in: aCa(OH)₂(aq) + CO₂(b) → CaCO₃(c) + dH₂O(l)

(A) a=2, b=g, c=s, d=2 (B) a=2, b=l, c=s, d=2 (C) a=1, b=g, c=aq, d=1 (D) a=1, b=g, c=s, d=1

Q4. Which are combination reactions?

(i) 2KClO₃ → 2KCl + 3O₂ (ii) MgO + H₂O → Mg(OH)₂ (iii) 4Al + 3O₂ → 2Al₂O₃ (iv) Zn + FeSO₄ → ZnSO₄ + Fe

(A) (i) and (iii) (B) (iii) and (iv) (C) (ii) and (iv) (D) (ii) and (iii)

Q5. Match combination reaction types

(a) Element + compound; (b) Compound + compound; (c) Element + element
(i) AB + CD → ABCD; (ii) A + B → AB; (iii) A + BC → ABC

(A) (a)-(i), (b)-(ii), (c)-(iii) (B) (a)-(ii), (b)-(i), (c)-(iii) (C) (a)-(iii), (b)-(i), (c)-(ii) (D) (a)-(iii), (b)-(ii), (c)-(i)

DHA 05 — Double Displacement and Precipitation

Focus: ion exchange, precipitate formation, reaction identification.

Q1. In Na₂SO₄ + BaCl₂ (aq) reaction:

Which statements are correct? (ii) exchange of ions, (iii) precipitate produced, (iv) insoluble salt produced

(A) (ii) and (iv) (B) (i) and (iii) (C) Only (ii) (D) (ii), (iii) and (iv)

Q2. Which is a double displacement reaction?

(i) Pb + CuCl₂ → PbCl₂ + Cu (ii) Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl (iii) C + O₂ → CO₂

(A) (i) and (ii) (B) Only (i) (C) Only (ii) (D) (ii) and (iii)

Q3. AgNO₃(aq) + NaCl(aq) produces:

(A) AgCl(aq) + NaNO₃(ppt) (B) AgNO₃(ppt) + NaNO₃(ppt) (C) AgCl(ppt) + NaNO₃(aq) (D) No reaction

Q4. BaCl₂ + (NH₄)₂SO₄ reaction type:

(A) Displacement (B) Precipitation (C) Double displacement (D) (ii) and (iv)

Q5. Which precipitate is not white?

(A) BaSO₄ (B) AgCl (C) CaCO₃ (D) PbI₂

Lead(II) iodide forms a yellow precipitate.

DHA 06 — Rusting, Redox, Oxidising Agents

Focus: rust colour, analogy for tarnish, redox identification, oxidising agents.

Q1. Rusting of iron forms a flaky layer of which colour?

(A) Green (B) Reddish-brown (C) Black (D) White

Q2. Copper: Patina :: Silver: X : Y

Identify X and Y by analogy.

(A) X: Tarnishing, Y: Patina (B) X: Patina, Y: Rusting (C) X: Rust, Y: Rusting (D) X: Patina, Y: Tarnishing

Q3. 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g) is an example of:

(A) Displacement and neutralisation (B) Combination and redox (C) Displacement and redox (D) Redox and neutralisation

Q4. For 3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g), which statements are correct?

(i) Iron is oxidised (ii) Water is reduced (iii) Water is reducing agent (iv) Water is oxidising agent

(A) (i), (ii) and (iii) (B) (iii) and (iv) (C) (i), (ii) and (iv) (D) (ii) and (iv)

Q5. Oxidising agent in Pb₃O₄ + 8HCl → 3PbCl₂ + Cl₂ + 4H₂O:

(A) Pb₃O₄ (B) HCl (C) PbCl₂ (D) H₂O

Built for quick practice and outreach. You can duplicate sections or rearrange for posters, app content, or LMS.

Acids, Bases and Salts

Item #3

DHA 01 — Chemical Reactions and Equations

Q1. Which of the following is a chemical change?

Q2. A chemical change may involve —

Q3. Which of the following is not a physical change?

Q4. Which of the following is/are true when milk changes into curd?

Q5. Which of the following does not involve a chemical reaction?

DHA 02 — Balancing and Stoichiometry

Q1. We balance equations to obey the:

Q2. Find the stoichiometric coefficients: aAl + bO₂ → cAl₂O₃

Q3. Find the stoichiometric coefficients: aH₂S + bO₂ → cH₂O + dSO₂

Q4. Find the stoichiometric coefficients: aNa₂SO₄ + bBaCl₂ → cBaSO₄ + dNaCl

DHA 03 — Endothermic/Exothermic, Types of Reactions

Q1. Which of the following is/are endothermic?

Q2. Which is not an exothermic reaction?

Q3. Identify the variables in: aCa(OH)₂(aq) + CO₂(b) → CaCO₃(c) + dH₂O(l)

Q4. Which are combination reactions?

Q5. Match combination reaction types

DHA 05 — Double Displacement and Precipitation

Q1. In Na₂SO₄ + BaCl₂ (aq) reaction:

Q2. Which is a double displacement reaction?

Q3. AgNO₃(aq) + NaCl(aq) produces:

Q4. BaCl₂ + (NH₄)₂SO₄ reaction type:

Q5. Which precipitate is not white?

DHA 06 — Rusting, Redox, Oxidising Agents

Q1. Rusting of iron forms a flaky layer of which colour?

Q2. Copper: Patina :: Silver: X : Y

Q3. 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g) is an example of:

Q4. For 3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g), which statements are correct?

Q5. Oxidising agent in Pb₃O₄ + 8HCl → 3PbCl₂ + Cl₂ + 4H₂O:

JEE MAINS