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Let's solve each multiple-choice question from the worksheet "Acid, Bases & Salts" and explain the reasoning behind each answer.

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(1) Plants in my garden were not bearing flowers and appeared dull despite all the care I took. I treated the soil solution with litmus and it turned red. What should I add to the soil to ensure better growth of plants?

- Litmus turned red → Soil is acidic
- To improve plant growth, we need to neutralize the acidity.
- Slaked lime (Ca(OH)₂) is a base used to neutralize acidic soils.

✔ Correct Answer: (B) Slaked lime

> Explanation: Acids turn blue litmus red. Since the soil is acidic, adding a base like slaked lime will reduce acidity and help plants grow better.

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(2) An example of an acid derived from a mineral is:

- Mineral acids are acids obtained from minerals (inorganic sources).
- Nitric acid (HNO₃) is made from nitrogen-containing minerals.
- Citric, acetic, and tartaric acids are organic acids (from plants or biological sources).

✔ Correct Answer: (B) Nitric Acid

> Explanation: Nitric acid is a strong mineral acid produced industrially from ammonia via the Ostwald process. Others are organic acids.

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(3) An acid present in aerated drinks:

- Aerated (carbonated) drinks contain dissolved carbon dioxide (CO₂), which reacts with water to form carbonic acid (H₂CO₃).
- CO₂ + H₂O → H₂CO₃

✔ Correct Answer: (C) Carbonic Acid

> Explanation: Carbonic acid gives carbonated drinks their fizz and slightly sour taste.

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(4) For burning sensation in the stomach which type of medicine is used?

- Burning sensation in the stomach is due to excess gastric acid (HCl).
- This condition is called acid reflux or heartburn.
- Antacids neutralize stomach acid.

✔ Correct Answer: (C) Antacid

> Explanation: Antacids like milk of magnesia or calcium carbonate react with HCl to relieve discomfort.

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(5) Blood is:

- Human blood has a pH around 7.35–7.45, which is slightly basic.
- It must remain slightly alkaline for proper physiological function.

✔ Correct Answer: (B) Basic

> Explanation: Even though it’s close to neutral, blood is considered slightly basic. If it becomes too acidic or basic, it can be dangerous.

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(6) Which of these if heated in an aluminium pan would corrode the pan most?

- Aluminium reacts with acids to produce hydrogen gas.
- Among the options:
- Tomato juice is highly acidic (contains citric acid).
- Eggs and milk are slightly acidic or neutral.
- Water is neutral.

→ Tomato juice will react with aluminium and cause corrosion.

✔ Correct Answer: (C) Tomato juice

> Explanation: Acids react with metals like aluminium to form salts and hydrogen gas. Tomato juice contains citric acid, making it the most corrosive here.

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(7) If lemon juice is mixed with marble chips, it will dissolve some of the marble chips.

- Lemon juice contains citric acid.
- Marble chips are made of calcium carbonate (CaCO₃).
- Acid + Carbonate → Salt + Water + CO₂
- Example: CaCO₃ + 2H⁺ → Ca²⁺ + H₂O + CO₂

✔ Answer: (A) True

> Explanation: The reaction between citric acid and calcium carbonate produces soluble calcium citrate, water, and carbon dioxide, so the marble chips will dissolve.

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(8) Sulphuric acid is used in car batteries.

- Yes, sulphuric acid (H₂SO₄) is a key component in lead-acid car batteries.
- It acts as the electrolyte.

✔ Answer: (A) True

> Explanation: In lead-acid batteries, sulfuric acid facilitates the electrochemical reactions that produce electricity.

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✔ Final Answers:

| Q.No | Answer |
|------|--------|
| (1) | B |
| (2) | B |
| (3) | C |
| (4) | C |
| (5) | B |
| (6) | C |
| (7) | A |
| (8) | A |

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