Top 10 Exam Questions From Acids, Bases And Salts (with Solutions)

Top 10 Questions from Acids, Bases and Salts

Why do I keep losing marks in this chapter?

You’ve memorized the definitions. You’ve done a few exercises. But when the exam paper hits your desk and the Acids, Bases and Salts questions appear — your mind suddenly goes blank. Sound familiar?

This chapter from Class 10 Science seems easy on the surface. After all, you’re surrounded by acids and bases daily — lemon juice, baking soda, soap, vinegar. So, what makes the exam questions so tricky?

Misunderstand one concept, and the whole chapter falls apart

Let’s be honest. A lot of students fall into a pattern: cram a few properties, mug up the pH scale, and hope the paper only asks “define an acid”. But CBSE questions go beyond definitions.

They ask for reasoning. They give you real-life examples. They demand application — not just theory.

If you don’t understand why baking soda feels soapy or how salts are formed, you can lose precious marks. Worse, this confusion can carry over into chemistry topics in higher classes. It also affects your practical understanding of day-to-day substances, like how to neutralize acidity or which cleaning agent to use.

So what’s the solution?

SOLUTION: Master the top 10 exam questions — with clear, step-by-step solutions

Let’s walk through the 10 most commonly asked questions from this chapter — with complete explanations. You’ll not only learn the correct answers, but why they’re correct. You’ll also get memory tricks and student-friendly breakdowns.

Question 1: Define acid and base with examples. Identify strong and weak types.

Why it's important: This forms the foundation. Everything else — from reactions to salt formation — starts here.

Step-by-step Solution:

• Acid: A substance that gives H⁺ ions in aqueous solution.
  • Example: Hydrochloric acid (HCl)
• Base: A substance that gives OH⁻ ions in aqueous solution.
  • Example: Sodium hydroxide (NaOH)

Strong Acid: Completely dissociates in water.
→ HCl, HNO₃
Weak Acid: Partially dissociates.
→ CH₃COOH (acetic acid)
Strong Base: Fully ionizes.
→ NaOH, KOH
Weak Base: Partial ionization.
→ NH₄OH (ammonium hydroxide)
Pro Tip: Use the phrase "Strong = fully dissociates". Think of it like a team that breaks into individual players quickly. Weak acids/bases stay as a group.

Question 2: Why does dry HCl gas not change the color of dry litmus paper?

Common error: Students say "because it's a gas" — which is wrong.
Correct Explanation:
Dry HCl does not release H⁺ ions unless it’s in aqueous form (dissolved in water). Since there's no water in dry litmus or dry gas, no ionization happens.
No H⁺ = No acid behavior = No color change.
Real-life Link: That’s why sniffing concentrated HCl doesn’t burn your nose instantly — it needs moisture to ionize.

Question 3: Explain the pH scale with examples of substances.

Key Concepts:

• Scale: 0 (strong acid) to 14 (strong base); 7 = neutral
• pH < 7 = Acidic; pH > 7 = Basic

Why this matters in exams: Questions often give you unknown substances and ask you to guess pH ranges.
Memory Tip: "Left = Lemon (acid), Right = Rinse (base), Center = Clean (water)"

Question 4: What happens when a base reacts with a non-metallic oxide?

This is a common HOTS (Higher Order Thinking Skill) question.
Step-by-step Reaction:
Let’s take: Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

• Ca(OH)₂ = Base
• CO₂ = Non-metal oxide
• Product = Salt (CaCO₃) + Water

Conclusion: Non-metal oxides are acidic in nature. They react with bases to form salt and water, just like acids do.
Real-Life Use: That’s how limewater detects CO₂ — it turns milky due to CaCO₃.

Question 5: What is the action of acids on metals?

General Reaction:

Acid + Metal → Salt + Hydrogen gas

Example:

Zn + 2HCl → ZnCl₂ + H₂↑

Test for H₂: Bring a burning splint near the gas → it gives a pop sound.
What to watch for: Don't say acid + metal gives only "gas". Specify hydrogen.

Question 6: Explain neutralization reaction with examples.

Definition:
When an acid reacts with a base to form salt and water, it's called neutralization.
Example:

NaOH + HCl → NaCl + H₂O

Applications:

• Antacids neutralize stomach acid.
• Farmers use quick lime (CaO) on acidic soil.

Case Study: A 2020 agricultural study showed that over-acidic soil in Tamil Nadu led to 22% crop reduction — neutralizing it restored productivity.

Question 7: Why do acids not show acidic behavior in absence of water?

Reasoning:
Because acids only ionize in water to give H⁺ ions. No water = no H⁺ = no acidity.
Experiment reference: Drop HCl in dry ethanol vs. in water — only the water solution turns blue litmus red.
Exam Clarity: Always mention "ionization in water is essential".

Question 8: What are salts? How are they classified?

Salt = Acid + Base reaction product

They are electrolytes formed when hydrogen ions in acid are replaced by metal or ammonium ions.
Types of salts:

1. Normal Salt: NaCl (from strong acid + strong base)
2. Acidic Salt: NaHSO₄ (from strong acid + weak base)
3. Basic Salt: ZnCO₃ (from weak acid + strong base)

In Class 10 Exams: Focus on types, examples, and whether salts are neutral, acidic, or basic.

Question 9: Give reasons – baking soda is used in antacids and fire extinguishers.

Concept Application:
In antacids:

• Baking soda (NaHCO₃) is mildly basic.
• It neutralizes stomach acid (HCl).

In fire extinguishers:

• Reacts with acid to release CO₂, which cuts off oxygen and douses flames.

Reaction:

NaHCO₃ + HCl → NaCl + CO₂ + H₂O

Link to Real World: This is why kitchen fire extinguishers often use dry chemical powder.

Question 10: Why should curd not be stored in metal containers?

Explanation:
Curd contains lactic acid. Metal containers like copper or aluminum react with acids → form metal salts, which are toxic.
Example Reaction:

Cu + H⁺ (from lactic acid) → Cu²⁺ + H₂

Health Risk: Metal salts can cause food poisoning.
Pro Tip: Always connect food safety to chemical reactivity. Teachers love real-life answers.

Summary Table – 10 Questions at a Glance

What should you do next?

• Practice these Qs again without looking at answers.
• Make mind maps for reactions and examples.
• Focus on “why” not just “what” — CBSE LOVES reasoning questions.

Bonus Tip: Turn each question into a flashcard — one side question, other side answer + reason.
Remember — acids, bases, and salts aren't just for the exam. They're in your kitchen, your medicine cabinet, even your cleaning supplies. Understand them well, and you're not just scoring better — you're thinking like a scientist.

For better practice, download the worksheet with questions and answers based on this post by clicking the button below.

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