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Question (31)

QN00751

Excessive use of chemical fertilisers made the soil acidic. Which substance should be added to improve the soil?

(A) Vinegar
(B) Lemon juice
(C) Lime
(D) Tamarind water

Correct Answer: C

Explanation:

Lime neutralises acidic soil.

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Question (32)

QN00752

If soil is basic in nature, farmers may add compost because it

(A) releases bases
(B) releases acids
(C) releases salts
(D) removes water

Correct Answer: B

Explanation:

Organic matter releases acids.

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Question (33)

QN00753

Fish in a lake were dying because acidic factory waste was released into it. What should be done before releasing the waste?

(A) Add more acid
(B) Add neutral water only
(C) Neutralise it with bases
(D) Heat the waste strongly

Correct Answer: C

Explanation:

Bases neutralise acidic waste.

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Question (34)

QN00754

Ashwin wrote a hidden message using a soap solution on turmeric-coated paper. Which colour would appear after spraying turmeric solution?

(A) Blue
(B) Green
(C) Red
(D) White

Correct Answer: C

Explanation:

Soap turns turmeric red.

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Question (35)

QN00755

Which of the following combinations correctly matches the indicator with its observation in a basic solution?

(A) Blue litmus → red
(B) Red rose extract → red
(C) Turmeric paper → yellow
(D) Red litmus → blue

Correct Answer: D

Explanation:

Bases turn red litmus blue.

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Question (36)

QN00756

A student tested a liquid using three indicators. Blue litmus turned red, turmeric showed no change, and red rose extract became reddish. The liquid is

(A) acidic
(B) basic
(C) neutral
(D) salty

Correct Answer: A

Explanation:

All observations indicate an acid.

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Question (37)

QN00757

Which scientist is known as the “Father of Modern Indian Chemistry”?

(A) C.V. Raman
(B) Homi Bhabha
(C) P.C. Ray
(D) Jagadish Chandra Bose

Correct Answer: C

Explanation:

P.C. Ray is called the Father of Modern Indian Chemistry.

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Question (38)

QN00758

P.C. Ray established India’s first pharmaceutical company in

(A) 1857
(B) 1901
(C) 1947
(D) 2001

Correct Answer: B

Explanation:

He established it in 1901.

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Question (39)

QN00759

A student observed that red rose extract did not change colour after adding sugar solution. The sugar solution is therefore

(A) acidic
(B) basic
(C) neutral
(D) slippery

Correct Answer: C

Explanation:

Neutral substances do not change red rose extract colour.

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Question (40)

QN00760

Aman poured vinegar on marble pieces and noticed bubbles, but soap solution produced no bubbles. This suggests that vinegar

(A) reacts with marble
(B) is neutral
(C) contains only water
(D) prevents chemical reactions

Correct Answer: A

Explanation:

Vinegar reacts with marble and releases bubbles.

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Question (31)

Excessive use of chemical fertilisers made the soil acidic. Which substance should be added to improve the soil?

Explanation:

Link:

Question (32)

If soil is basic in nature, farmers may add compost because it

Explanation:

Link:

Question (33)

Fish in a lake were dying because acidic factory waste was released into it. What should be done before releasing the waste?

Explanation:

Link:

Question (34)

Ashwin wrote a hidden message using a soap solution on turmeric-coated paper. Which colour would appear after spraying turmeric solution?

Explanation:

Link:

Question (35)

Which of the following combinations correctly matches the indicator with its observation in a basic solution?

Explanation:

Link:

Question (36)

A student tested a liquid using three indicators. Blue litmus turned red, turmeric showed no change, and red rose extract became reddish. The liquid is

Explanation:

Link:

Question (37)

Which scientist is known as the “Father of Modern Indian Chemistry”?

Explanation:

Link:

Question (38)

P.C. Ray established India’s first pharmaceutical company in

Explanation:

Link:

Question (39)

A student observed that red rose extract did not change colour after adding sugar solution. The sugar solution is therefore

Explanation:

Link:

Question (40)

Aman poured vinegar on marble pieces and noticed bubbles, but soap solution produced no bubbles. This suggests that vinegar

Explanation:

Link:

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