TNPSC Chemistry – Chemical Reactions Quiz 1

Concept Booster – TNPSC Chemistry Chemical Reactions Quiz

This Concept Booster for TNPSC Chemistry Chemical Reactions Quiz is designed to help you clearly understand the key concepts covered in the quiz. It explains important topics such as types of chemical reactions, oxidation and reduction, reactants and products, and real-life applications in a simple and exam-focused manner.

Go through this section after attempting the quiz to strengthen your fundamentals, improve accuracy, and perform better in TNPSC General Science questions.

A chemical reaction is a process in which one or more substances called reactants are transformed into new substances called products with different chemical properties. During a chemical reaction:

• Energy may be released or absorbed
• Bonds in reactants are broken
• New bonds are formed

Indicators of a Chemical Reaction

You can identify a chemical reaction by:

• Change in state
• Change in color
• Formation of a gas (bubbles)
• Formation of a precipitate (solid)
• Change in temperature (heat released/absorbed)

Types of Chemical Reactions (Very Important)

1. Combination Reaction

Two or more substances combine to form a single product.

Example: 2H₂ + O₂ → 2H₂O

👉 Easy to identify: Multiple → One

2.Decomposition Reaction

A single compound breaks down into simpler substances.

Example: CaCO₃ → CaO + CO₂

👉 Opposite of combination

Displacement Reaction

A more reactive element displaces a less reactive element.

Example:

Zn + CuSO₄ → ZnSO₄ + Cu

Double Displacement Reaction

Exchange of ions between two compounds.

Example: AgNO₃ + NaCl → AgCl (precipitate) + NaNO₃

👉 Often forms precipitate

Neutralization Reaction

Acid reacts with base to form salt and water.

Example: HCl + NaOH → NaCl + H₂O

Combustion Reaction

Substance reacts with oxygen releasing heat and light.

Example: CH₄ + O₂ → CO₂ + H₂O

Oxidation and Reduction (VERY IMPORTANT 🔥)

Oxidation:

• Addition of oxygen
• Removal of hydrogen
• Loss of electrons

Reduction:

• Removal of oxygen
• Addition of hydrogen
• Gain of electrons

👉 Both occur together → called Redox Reaction

Important Terminology

• Reactants → Starting substances
• Products → Final substances
• Precipitate → Insoluble solid formed in solution
• Catalyst → Speeds up reaction without being consumed

Law of Conservation of Mass

This law states that:

👉 Mass is neither created nor destroyed in a chemical reaction

Total mass of reactants = Total mass of products

This is why balancing chemical equations is important.

Real-Life Examples

Understanding real-life applications makes questions easy:

• Rusting of iron → Oxidation reaction (very important)
• Burning of magnesium ribbon → Produces white ash (MgO)
• Zinc + Hydrochloric acid → Produces hydrogen gas
• Curd formation from milk → Chemical change
• Digestion of food → Decomposition reactions
• Combustion of LPG → Used in cooking
• Antacids in stomach → Neutralization reaction

👉 TNPSC frequently asks from these examples.

Easy Memory Tricks for Chemical Reactions:

1. Types of Chemical Reactions Trick

👉 Remember this keyword: “CDDDR”

👉 Meaning:

• C → Combination
• D → Decomposition
• D → Displacement
• D → Double Displacement
• R → Redox

🧠 Trick sentence:
“Cool Dogs Do Dance Regularly”

2. Oxidation vs Reduction Trick

👉 Remember: OIL RIG

• OIL → Oxidation Is Loss (of electrons)
• RIG → Reduction Is Gain (of electrons)

🔥 Very important — TNPSC favorite question

3. Reactants vs Products Trick

👉 Think like cooking:

• Reactants → Ingredients
• Products → Final dish

🧠 Easy line: “Start = Reactants, End = Products”

4. Combination vs Decomposition

👉 Opposite concepts:

• Combination → Many → One
• Decomposition → One → Many

🧠 Trick:
“Come Together → Combine”
“Break Apart → Decompose”

5. Displacement Reaction Trick

👉 Strong replaces weak

🧠 Trick: “Powerful element pushes out weaker one”

Example: Zinc replaces Copper

6. Neutralization Reaction Trick

👉 Remember: “Acid + Base = Peace” ☮️

Meaning: Acid + Base → Salt + Water

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7. Rusting Trick

👉 Remember: “IRON + OXYGEN = RUST”

🧠 Shortcut: Rust = Oxidation

8. Precipitate Trick

👉 Hard word → simple meaning:

“Precipitate = Solid formed in liquid”

9. Law of Conservation of Mass

👉 Remember: “Nothing is lost, nothing is gained”

🧠 Shortcut: Mass before = Mass after

10. Combustion Reaction Trick

👉 Remember: “Burning needs Oxygen”

🧠 Trick:
Fuel + O₂ → Heat + Light

Final Revision Tips

👉 Most TNPSC questions are concept-based, not complicated

Recommended Reference

For a deeper understanding of chemical reactions, you can refer to this detailed explanation on Byju’s.