Consider the following phenomena: 1. Photosynthesis 2. Digestion of food 3. Fermentation of grapes 4. Ripening of fruits Which of the above are classified as chemical changes?

Correct Option The correct option is (d). Explanation A chemical change is a process where one or more substances are transformed into new substances with different chemical properties. Unlike physical changes, chemical changes involve the breaking and making of chemical bonds and are generally irreversible. Statement-wise Analysis - 1. Photosynthesis: Correct. This is a biochemical process where green plants synthesize nutrients from carbon dioxide and water in the presence of sunlight and chlorophyll. New substances (glucose and oxygen) are formed, making it a chemical change. - 2. Digestion of food: Correct. Digestion involves the breakdown of complex food molecules (carbohydrates, proteins, fats) into simpler substances (glucose, amino acids, fatty acids) through the action of enzymes and acids. Since the chemical composition of the food changes, it is a chemical change. - 3. Fermentation of grapes: Correct. Fermentation is a metabolic process where enzymes (often from yeast) convert sugars into alcohol (ethanol) and carbon dioxide. This results in the formation of entirely new chemical compounds. - 4. Ripening of fruits: Correct. Ripening involves a series of chemical reactions, such as the breakdown of starch into sugars and the degradation of chlorophyll. These reactions alter the taste, texture, and color of the fruit permanently, constituting a chemical change. Key Takeaway: Any process that results in the formation of new substances with distinct chemical identities and cannot be easily reversed by physical means is classified as a chemical change.

NCERT Class 7 Science — Chapter 2: Physical and chemical changes

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Consider the following phenomena:

Photosynthesis
Digestion of food
Fermentation of grapes
Ripening of fruits

Which of the above are classified as chemical changes?

Official previous-year question

Verified 1 Aug 2026.

Options

A1 and 2 only
B2 and 3 only
C3 and 4 only
D1, 2, 3 and 4

Did you get this right?

Solution

Correct Option

The correct option is (d).

Explanation

A chemical change is a process where one or more substances are transformed into new substances with different chemical properties. Unlike physical changes, chemical changes involve the breaking and making of chemical bonds and are generally irreversible.

Statement-wise Analysis

1. Photosynthesis: Correct. This is a biochemical process where green plants synthesize nutrients from carbon dioxide and water in the presence of sunlight and chlorophyll. New substances (glucose and oxygen) are formed, making it a chemical change.
2. Digestion of food: Correct. Digestion involves the breakdown of complex food molecules (carbohydrates, proteins, fats) into simpler substances (glucose, amino acids, fatty acids) through the action of enzymes and acids. Since the chemical composition of the food changes, it is a chemical change.
3. Fermentation of grapes: Correct. Fermentation is a metabolic process where enzymes (often from yeast) convert sugars into alcohol (ethanol) and carbon dioxide. This results in the formation of entirely new chemical compounds.
4. Ripening of fruits: Correct. Ripening involves a series of chemical reactions, such as the breakdown of starch into sugars and the degradation of chlorophyll. These reactions alter the taste, texture, and color of the fruit permanently, constituting a chemical change.

Key Takeaway: Any process that results in the formation of new substances with distinct chemical identities and cannot be easily reversed by physical means is classified as a chemical change.

Your note

More from Chapter 2: Physical and chemical changes

With reference to the burning of a magnesium ribbon, consider the following statements: 1. It burns with a dull blue flame. 2. The ash formed is chemically different from the magnesium ribbon. 3. The reaction produces a new substance called magnesium oxide. Which of the statements given above is/are correct?

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When the ash obtained from burning magnesium is dissolved in water, the resulting solution is:

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With reference to the reaction between Copper Sulphate and Iron, consider the following statements: 1. The colour of the solution changes from blue to green. 2. The green colour is due to the formation of Copper Oxide. 3. A brown deposit forms on the iron object, which is Rust (Iron Oxide). Which of the statements given above is/are correct?

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Which of the following pairs is correctly matched regarding the reaction of Copper Sulphate with Iron?

easy

With reference to the "Lime Water Test", consider the following statements: 1. It is a standard test for Carbon Dioxide gas. 2. The milky appearance is due to the formation of Calcium Oxide. 3. The chemical name of lime water is Calcium Hydroxide. Which of the statements given above is/are correct?

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Correct Option

The correct option is (d).

Explanation

Statement-wise Analysis

1. Photosynthesis: Correct. This is a biochemical process where green plants synthesize nutrients from carbon dioxide and water in the presence of sunlight and chlorophyll. New substances (glucose and oxygen) are formed, making it a chemical change.
2. Digestion of food: Correct. Digestion involves the breakdown of complex food molecules (carbohydrates, proteins, fats) into simpler substances (glucose, amino acids, fatty acids) through the action of enzymes and acids. Since the chemical composition of the food changes, it is a chemical change.
3. Fermentation of grapes: Correct. Fermentation is a metabolic process where enzymes (often from yeast) convert sugars into alcohol (ethanol) and carbon dioxide. This results in the formation of entirely new chemical compounds.
4. Ripening of fruits: Correct. Ripening involves a series of chemical reactions, such as the breakdown of starch into sugars and the degradation of chlorophyll. These reactions alter the taste, texture, and color of the fruit permanently, constituting a chemical change.

Key Takeaway: Any process that results in the formation of new substances with distinct chemical identities and cannot be easily reversed by physical means is classified as a chemical change.