Consider the following statements about 'Organic Matter' used in soil treatment: 1. It is added to acidic soil to neutralize it. 2. It releases acids which neutralize the basic nature of the soil. Which of the statements given above is/are correct?

The correct option is (b) 2 only. Explanation Soil reaction (pH) determines the availability of nutrients to plants. Soil amendments are chemical or organic substances added to the soil to adjust its pH level-either to reduce acidity or alkalinity-to create an optimal environment for crop growth. Statement-wise Analysis: - Statement 1 is Incorrect: Acidic soils are characterized by a low pH and an excess of hydrogen ions. To neutralize acidic soil, basic substances are required. Common treatments involve the application of bases such as quick lime (Calcium oxide) or slaked lime (Calcium hydroxide), which react with the acids in the soil to raise the pH. Adding organic matter, which releases acids, would not be the primary method to neutralize acidity. - Statement 2 is Correct: Organic matter (such as compost or manure) undergoes decomposition by soil microorganisms. This process releases organic acids. These acids react with the excess bases present in alkaline (basic) soils, thereby neutralizing the basicity and lowering the soil pH towards a neutral range. Key Takeaway: Bases (like lime) are used to treat acidic soils, whereas organic matter (which releases acids) is used to treat basic soils.

NCERT Class 7 Science — Chapter 1: Acids, bases and salts

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Consider the following statements about 'Organic Matter' used in soil treatment:

It is added to acidic soil to neutralize it.
It releases acids which neutralize the basic nature of the soil.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A1 only
B2 only
CBoth 1 and 2
DNeither 1 nor 2

Did you get this right?

Solution

The correct option is (b) 2 only.

Explanation

Soil reaction (pH) determines the availability of nutrients to plants. Soil amendments are chemical or organic substances added to the soil to adjust its pH level-either to reduce acidity or alkalinity-to create an optimal environment for crop growth.

Statement-wise Analysis:

Statement 1 is Incorrect: Acidic soils are characterized by a low pH and an excess of hydrogen ions. To neutralize acidic soil, basic substances are required. Common treatments involve the application of bases such as quick lime (Calcium oxide) or slaked lime (Calcium hydroxide), which react with the acids in the soil to raise the pH. Adding organic matter, which releases acids, would not be the primary method to neutralize acidity.
Statement 2 is Correct: Organic matter (such as compost or manure) undergoes decomposition by soil microorganisms. This process releases organic acids. These acids react with the excess bases present in alkaline (basic) soils, thereby neutralizing the basicity and lowering the soil pH towards a neutral range.

Key Takeaway:
Bases (like lime) are used to treat acidic soils, whereas organic matter (which releases acids) is used to treat basic soils.

Your note

More from Chapter 1: Acids, bases and salts

With reference to the chemical nature of substances, consider the following statements: 1. All substances that taste sour contain acids. 2. Substances that taste bitter and feel soapy on touching are generally acidic in nature. 3. Baking soda is an example of a substance that has a bitter taste and is basic in chemical nature. Which of the statements given above is/are correct?

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Consider the following statements regarding naturally occurring acids: 1. Lactic acid is the primary constituent of vinegar. 2. Oxalic acid is found in spinach. 3. Ascorbic acid is also known as Vitamin C. Which of the statements given above is/are correct?

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Which one of the following pairs is correctly matched regarding the acid present in the substance?

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With reference to bases and their sources, consider the following pairs: 1. Calcium hydroxide : Lime water 2. Ammonium hydroxide : Window cleaner 3. Magnesium hydroxide : Soap 4. Sodium hydroxide : Milk of magnesia How many of the above pairs are correctly matched?

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Consider the following statements about 'Litmus', a natural indicator: 1. It is extracted from lichens. 2. It has a green colour in distilled water. 3. It turns blue when added to an acidic solution. Which of the statements given above is/are correct?

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The correct option is (b) 2 only.

Explanation

Statement-wise Analysis:

Statement 1 is Incorrect: Acidic soils are characterized by a low pH and an excess of hydrogen ions. To neutralize acidic soil, basic substances are required. Common treatments involve the application of bases such as quick lime (Calcium oxide) or slaked lime (Calcium hydroxide), which react with the acids in the soil to raise the pH. Adding organic matter, which releases acids, would not be the primary method to neutralize acidity.
Statement 2 is Correct: Organic matter (such as compost or manure) undergoes decomposition by soil microorganisms. This process releases organic acids. These acids react with the excess bases present in alkaline (basic) soils, thereby neutralizing the basicity and lowering the soil pH towards a neutral range.

Key Takeaway:
Bases (like lime) are used to treat acidic soils, whereas organic matter (which releases acids) is used to treat basic soils.