Chemical Bonds and Reactions – Class 10 Guide With MCQs

🌟 Chemical Bonds and Reactions

Understanding chemical bonds and reactions is essential for Class 10 science students. These topics form the foundation of Chemistry and are frequently tested in board exams. Let’s dive into the concepts in a simple and structured way.

🧪 What is a Chemical Bond? Chemical Bonds

A chemical bond is a force that holds atoms together in a molecule or compound. Atoms form bonds to become more stable by completing their outermost electron shells.

Also, Read>> Science Education: Innovations, Challenges, and Future Directions

🔗 Types of Chemical Bonds

💡 Illustrative Example: Chemical Bonds

Ionic Bond (NaCl)
Sodium (Na) gives away 1 electron to Chlorine (Cl). Na becomes Na⁺ and Cl becomes Cl⁻, forming NaCl.

Illustration Description:

• Another circle, “Cl” gains the electron
• One circle labeled “Na” loses an electron (arrow shows transfer)
• Result: oppositely charged ions attract

🔥 What is a Chemical Reaction?

A chemical reaction is a process where one or more substances (reactants) change into new substances (products) with different properties.

🧬 General Representation:

Reactants → Products

Example:
H₂ + O₂ → H₂O

⚗️ Types of Chemical Reactions (Class 10 Focus)

🧠 How to Balance a Chemical Equation

Steps:

1. Write the unbalanced equation.
2. Count atoms on both sides.
3. Add coefficients to balance atoms.
4. Ensure mass and charge are balanced.

Example:
Unbalanced: H₂ + O₂ → H₂O
Balanced: 2H₂ + O₂ → 2H₂O

✅ Quick Recap Table

📚 Practice MCQs (Multiple Choice Questions) About Chemical Bonds

1. What happens to atoms during a chemical reaction?
A) They disappear
B) They change shape
C) They rearrange to form new substances
D) They melt
✅ Answer: C) They rearrange to form new substances

2. Which of these compounds contains a covalent bond?
A) NaCl
B) HCl
C) MgO
D) CaCl₂
✅ Answer: B) HCl

3. Which of the following is a balanced chemical equation?
A) H₂ + O₂ → H₂O
B) 2H₂ + O₂ → 2H₂O
C) H₂ + O₂ → 2H₂O₂
D) 2H₂ + 2O₂ → H₂O
✅ Answer: B) 2H₂ + O₂ → 2H₂O

4. Which reaction is an example of a combination reaction?
A) CaCO₃ → CaO + CO₂
B) Zn + HCl → ZnCl₂ + H₂
C) C + O₂ → CO₂
D) AgNO₃ + NaCl → AgCl + NaNO₃
✅ Answer: C) C + O₂ → CO₂

5. What type of reaction is 2KClO₃ → 2KCl + 3O₂?
A) Displacement
B) Double Displacement
C) Combination
D) Decomposition
✅ Answer: D) Decomposition

6. Which substance is oxidized in the reaction: Zn + CuSO₄ → ZnSO₄ + Cu?
A) Cu
B) Zn
C) SO₄
D) ZnSO₄
✅ Answer: B) Zn

7. What is always conserved in a balanced chemical reaction?
A) Volume
B) Mass
C) Temperature
D) Pressure
✅ Answer: B) Mass

8. The bond formed by equal sharing of electrons is called:
A) Polar covalent bond
B) Non-polar covalent bond
C) Ionic bond
D) Coordinate bond
✅ Answer: B) Non-polar covalent bond

9. An element that gains electrons during bonding becomes a:
A) Cation
B) Anion
C) Proton
D) Neutron
✅ Answer: B) Anion

10. In which of the following compounds is a metallic bond found?
A) NaCl
B) H₂O
C) Cu
D) NH₃
✅ Answer: C) Cu

11. Which is not a characteristic of chemical reactions?
A) Change in state
B) Evolution of gas
C) Formation of new products
D) Change in atomic number
✅ Answer: D) Change in atomic number

12. Which of the following is a double displacement reaction?
A) 2KClO₃ → 2KCl + 3O₂
B) BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl
C) Zn + H₂SO₄ → ZnSO₄ + H₂
D) 2H₂ + O₂ → 2H₂O
✅ Answer: B) BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl

13. Which of the following ions has a full outer shell?
A) Na⁺
B) O
C) Cl
D) Mg
✅ Answer: A) Na⁺

14. Which metal reacts with hydrochloric acid to produce hydrogen gas?
A) Copper
B) Silver
C) Zinc
D) Gold
✅ Answer: C) Zinc

15. What is the product of the reaction between HCl and NaOH?
A) H₂
B) NaCl
C) H₂O
D) Both B and C
✅ Answer: D) Both B and C

16. Which of the following is an example of an ionic bond?
A) H₂O
B) CO₂
C) NaCl
D) CH₄
✅ Answer: C) NaCl

17. In a decomposition reaction:
A) Two elements combine
B) One compound breaks down
C) Two compounds exchange ions
D) One element replaces another
✅ Answer: B) One compound breaks down

18. Which of the following is a redox reaction?
A) H₂ + Cl₂ → 2HCl
B) AgNO₃ + NaCl → AgCl + NaNO₃
C) CaCO₃ → CaO + CO₂
D) NaOH + HCl → NaCl + H₂O
✅ Answer: A) H₂ + Cl₂ → 2HCl

19. Covalent bonds are formed by:
A) Transfer of electrons
B) Sharing of electrons
C) Loss of protons
D) Loss of neutrons
✅ Answer: B) Sharing of electrons

20. The reaction: Zn + CuSO₄ → ZnSO₄ + Cu is:
A) Combination
B) Double displacement
C) Decomposition
D) Displacement
✅ Answer: D) Displacement

❓ Frequently Asked Questions (FAQs)

Q1. Why do atoms form bonds?
Atoms form bonds to achieve a full outer shell of electrons, which makes them more stable.

Q2. What is the difference between ionic and covalent bonds?
Ionic bonds involve the transfer of electrons (between metals and non-metals), while covalent bonds involve the sharing of electrons (between non-metals).

Q3. Are all chemical reactions visible?
Not always. Some reactions are visible (color change, gas formation), others are microscopic or require indicators.

Q4. How can I identify the type of reaction?
Look at the reactants and products. The pattern of change (combine, break, swap) helps determine the reaction type.

Q5. What is a catalyst in a chemical reaction?
A catalyst speeds up the reaction without being consumed in it.

Chemical Bonds