Physical and Chemical Changes MCQ Quiz - Objective Question with Answer for Physical and Chemical Changes - Download Free PDF

The correct answer is Statements I and III are correct. 

Key Points

• Statement I: The boiling of water is a physical change as it involves a change in the state from liquid to gas without altering the chemical composition of water.
• Statement III: The cooking of food is a chemical change because it involves various chemical reactions that alter the original substances and produce new substances with different properties.
• Statement II is incorrect as the rusting of iron is a chemical change where iron reacts with oxygen and moisture to form iron oxide, a new substance.
• Physical changes involve changes in physical properties such as shape, state, and size, without altering the substance's chemical identity.

Additional Information

• Chemical Change
  • A chemical change results in the formation of one or more new substances with different chemical properties and compositions.
  • Examples include rusting of iron, burning of wood, and digestion of food.
• Physical Change
  • A physical change affects the form of a chemical substance but not its chemical composition.
  • Examples include melting of ice, boiling of water, and dissolving sugar in water.
• Rusting of Iron
  • Rusting is a chemical reaction between iron, oxygen, and water, leading to the formation of iron oxide (rust).
  • This process is an example of corrosion, which deteriorates metals over time.
• Cooking of Food
  • Cooking involves chemical reactions such as caramelization, Maillard reaction, and denaturation of proteins.
  • These reactions change the flavor, texture, and nutritional properties of the food.

The correct answer is 1) Both Assertion and Reason are correct, and Reason is the correct explanation for Assertion..

Key Points

• Physical changes can often be reversed because they do not alter the chemical structure of a substance (e.g., melting ice).
• Chemical changes result in the formation of new substances with different chemical properties, making them generally irreversible (e.g., burning paper).
• In a physical change, the substance retains its original identity, as no new substances are formed.
• The reason provided correctly explains the assertion, as the reversibility of physical changes is tied to the fact that no new chemical bonds are formed or broken.
• The concept aligns with fundamental principles of chemistry, distinguishing physical and chemical changes based on molecular transformations.

Additional Information

• Physical Changes:
  • Examples include melting, boiling, freezing, condensation, and dissolving.
  • Physical changes are often reversible as no chemical composition is altered.
  • They involve changes in state, shape, or size.
• Chemical Changes:
  • Examples include rusting of iron, digestion of food, and combustion of wood.
  • Chemical changes involve breaking and forming new chemical bonds, resulting in new substances.
  • These changes are generally irreversible under normal conditions.
• Indicators of Chemical Changes:
  • Color change, gas production, temperature change, and formation of precipitate are key indicators.
  • Energy is often absorbed or released in the form of heat, light, or sound.
• Reversibility in Physical vs. Chemical Changes:
  • While most physical changes are reversible, some, like breaking glass, may be irreversible practically.
  • Chemical changes are usually irreversible because they involve new substances with different molecular structures.

The correct answer is B only.

Key Points

• Rusting of iron is a chemical change as it involves the formation of a new substance, iron oxide, which is different from the original material.
• Chemical changes result in the production of one or more new substances with different properties from the original substances.
• During rusting, iron reacts with oxygen and moisture in the environment, leading to corrosion.
• This process is irreversible under normal conditions, further confirming it as a chemical change.

Additional Information

• Physical vs Chemical Change
  • Physical changes affect the form of a chemical substance but not its chemical composition (e.g., melting ice).
  • Chemical changes involve making or breaking of bonds between atoms, resulting in new substances (e.g., burning wood).
• Indicators of Chemical Changes
  • Change in color, temperature, formation of a precipitate, and evolution of gas are common indicators.
  • Production of light or sound can also indicate a chemical change.
• Examples of Chemical Changes
  • Burning of paper, digestion of food, and baking a cake are classic examples.
  • These processes produce new substances with different properties from the reactants.
• Importance of Understanding Chemical Changes
  • Helps in various industries such as pharmaceuticals, agriculture, and manufacturing.
  • Understanding these changes is crucial in environmental science to address issues like pollution and recycling.

The correct answer is Denaturation.

Key Points

• Denaturation is the process where proteins lose their native structure due to external stress or compound, such as heat, strong acids or bases, organic solvents, or radiation.
• During denaturation, the proteins' secondary, tertiary, or quaternary structures are disrupted, leading to loss of function.
• This process is often irreversible, meaning that the protein cannot return to its original form.
• Denatured proteins tend to aggregate and precipitate out of solution, which can affect biological processes and functions.
• Common examples of denaturation include the cooking of an egg, where heat causes the egg whites to become solid and opaque.

Additional Information

• Degradation: This refers to the breakdown of proteins into their constituent amino acids or smaller peptides, often by enzymatic action.
• Spoilage: This term is typically used in the context of food, where microbial growth leads to the degradation and decay of food items, making them unfit for consumption.
• Renaturation: This is the process by which denatured proteins can sometimes regain their native structure and functional state under certain conditions.
• Protein Structure: Proteins have four levels of structure: primary (amino acid sequence), secondary (alpha-helices and beta-sheets), tertiary (3D shape), and quaternary (assembly of multiple polypeptides).
• Heat Shock Proteins (HSPs): These are a group of proteins that help protect other proteins during heat stress by aiding in proper folding and preventing aggregation.

The correct answer is physical, chemical.

Key Points

• Formation of a mixture is a physical change because the components of the mixture retain their individual properties and can be separated by physical means.
• Examples of mixtures include air, salt water, and alloys. These can be separated through physical processes such as filtration, evaporation, and distillation.
• Formation of a compound is a chemical change because it involves the formation of new substances with different properties from the original substances.
• In a chemical change, the original substances undergo a chemical reaction and form new substances that cannot be separated by physical means.
• Examples of compounds include water (H₂O), carbon dioxide (CO₂), and sodium chloride (NaCl). These can only be separated into their elements by chemical methods.

 Additional Information

• Physical Change
  • Physical changes do not alter the chemical composition of a substance.
  • They are usually reversible and do not involve the formation of new substances.
  • Examples include changes in state (melting, freezing, boiling), size (cutting, grinding), and shape.
• Chemical Change
  • Chemical changes result in the formation of one or more new substances with different chemical properties.
  • They are typically irreversible under normal conditions.
  • Indicators of a chemical change include color change, gas production, formation of a precipitate, and energy change (heat, light).

The correct answer is B only.

Key Points

• Rusting of iron is a chemical change as it involves the formation of a new substance, iron oxide, which is different from the original material.
• Chemical changes result in the production of one or more new substances with different properties from the original substances.
• During rusting, iron reacts with oxygen and moisture in the environment, leading to corrosion.
• This process is irreversible under normal conditions, further confirming it as a chemical change.

Additional Information

• Physical vs Chemical Change
  • Physical changes affect the form of a chemical substance but not its chemical composition (e.g., melting ice).
  • Chemical changes involve making or breaking of bonds between atoms, resulting in new substances (e.g., burning wood).
• Indicators of Chemical Changes
  • Change in color, temperature, formation of a precipitate, and evolution of gas are common indicators.
  • Production of light or sound can also indicate a chemical change.
• Examples of Chemical Changes
  • Burning of paper, digestion of food, and baking a cake are classic examples.
  • These processes produce new substances with different properties from the reactants.
• Importance of Understanding Chemical Changes
  • Helps in various industries such as pharmaceuticals, agriculture, and manufacturing.
  • Understanding these changes is crucial in environmental science to address issues like pollution and recycling.

The correct answer is physical, chemical.

Key Points

• Formation of a mixture is a physical change because the components of the mixture retain their individual properties and can be separated by physical means.
• Examples of mixtures include air, salt water, and alloys. These can be separated through physical processes such as filtration, evaporation, and distillation.
• Formation of a compound is a chemical change because it involves the formation of new substances with different properties from the original substances.
• In a chemical change, the original substances undergo a chemical reaction and form new substances that cannot be separated by physical means.
• Examples of compounds include water (H₂O), carbon dioxide (CO₂), and sodium chloride (NaCl). These can only be separated into their elements by chemical methods.

 Additional Information

• Physical Change
  • Physical changes do not alter the chemical composition of a substance.
  • They are usually reversible and do not involve the formation of new substances.
  • Examples include changes in state (melting, freezing, boiling), size (cutting, grinding), and shape.
• Chemical Change
  • Chemical changes result in the formation of one or more new substances with different chemical properties.
  • They are typically irreversible under normal conditions.
  • Indicators of a chemical change include color change, gas production, formation of a precipitate, and energy change (heat, light).

The correct answer is B only.

Key Points

• Rusting of iron is a chemical change as it involves the formation of a new substance, iron oxide, which is different from the original material.
• Chemical changes result in the production of one or more new substances with different properties from the original substances.
• During rusting, iron reacts with oxygen and moisture in the environment, leading to corrosion.
• This process is irreversible under normal conditions, further confirming it as a chemical change.

Additional Information

• Physical vs Chemical Change
  • Physical changes affect the form of a chemical substance but not its chemical composition (e.g., melting ice).
  • Chemical changes involve making or breaking of bonds between atoms, resulting in new substances (e.g., burning wood).
• Indicators of Chemical Changes
  • Change in color, temperature, formation of a precipitate, and evolution of gas are common indicators.
  • Production of light or sound can also indicate a chemical change.
• Examples of Chemical Changes
  • Burning of paper, digestion of food, and baking a cake are classic examples.
  • These processes produce new substances with different properties from the reactants.
• Importance of Understanding Chemical Changes
  • Helps in various industries such as pharmaceuticals, agriculture, and manufacturing.
  • Understanding these changes is crucial in environmental science to address issues like pollution and recycling.

The correct answer is Denaturation.

Key Points

• Denaturation is the process where proteins lose their native structure due to external stress or compound, such as heat, strong acids or bases, organic solvents, or radiation.
• During denaturation, the proteins' secondary, tertiary, or quaternary structures are disrupted, leading to loss of function.
• This process is often irreversible, meaning that the protein cannot return to its original form.
• Denatured proteins tend to aggregate and precipitate out of solution, which can affect biological processes and functions.
• Common examples of denaturation include the cooking of an egg, where heat causes the egg whites to become solid and opaque.

Additional Information

• Degradation: This refers to the breakdown of proteins into their constituent amino acids or smaller peptides, often by enzymatic action.
• Spoilage: This term is typically used in the context of food, where microbial growth leads to the degradation and decay of food items, making them unfit for consumption.
• Renaturation: This is the process by which denatured proteins can sometimes regain their native structure and functional state under certain conditions.
• Protein Structure: Proteins have four levels of structure: primary (amino acid sequence), secondary (alpha-helices and beta-sheets), tertiary (3D shape), and quaternary (assembly of multiple polypeptides).
• Heat Shock Proteins (HSPs): These are a group of proteins that help protect other proteins during heat stress by aiding in proper folding and preventing aggregation.

The correct answer is Statements I and III are correct. 

Key Points

• Statement I: The boiling of water is a physical change as it involves a change in the state from liquid to gas without altering the chemical composition of water.
• Statement III: The cooking of food is a chemical change because it involves various chemical reactions that alter the original substances and produce new substances with different properties.
• Statement II is incorrect as the rusting of iron is a chemical change where iron reacts with oxygen and moisture to form iron oxide, a new substance.
• Physical changes involve changes in physical properties such as shape, state, and size, without altering the substance's chemical identity.

Additional Information

• Chemical Change
  • A chemical change results in the formation of one or more new substances with different chemical properties and compositions.
  • Examples include rusting of iron, burning of wood, and digestion of food.
• Physical Change
  • A physical change affects the form of a chemical substance but not its chemical composition.
  • Examples include melting of ice, boiling of water, and dissolving sugar in water.
• Rusting of Iron
  • Rusting is a chemical reaction between iron, oxygen, and water, leading to the formation of iron oxide (rust).
  • This process is an example of corrosion, which deteriorates metals over time.
• Cooking of Food
  • Cooking involves chemical reactions such as caramelization, Maillard reaction, and denaturation of proteins.
  • These reactions change the flavor, texture, and nutritional properties of the food.

The correct answer is 1) Both Assertion and Reason are correct, and Reason is the correct explanation for Assertion..

Key Points

• Physical changes can often be reversed because they do not alter the chemical structure of a substance (e.g., melting ice).
• Chemical changes result in the formation of new substances with different chemical properties, making them generally irreversible (e.g., burning paper).
• In a physical change, the substance retains its original identity, as no new substances are formed.
• The reason provided correctly explains the assertion, as the reversibility of physical changes is tied to the fact that no new chemical bonds are formed or broken.
• The concept aligns with fundamental principles of chemistry, distinguishing physical and chemical changes based on molecular transformations.

Additional Information

• Physical Changes:
  • Examples include melting, boiling, freezing, condensation, and dissolving.
  • Physical changes are often reversible as no chemical composition is altered.
  • They involve changes in state, shape, or size.
• Chemical Changes:
  • Examples include rusting of iron, digestion of food, and combustion of wood.
  • Chemical changes involve breaking and forming new chemical bonds, resulting in new substances.
  • These changes are generally irreversible under normal conditions.
• Indicators of Chemical Changes:
  • Color change, gas production, temperature change, and formation of precipitate are key indicators.
  • Energy is often absorbed or released in the form of heat, light, or sound.
• Reversibility in Physical vs. Chemical Changes:
  • While most physical changes are reversible, some, like breaking glass, may be irreversible practically.
  • Chemical changes are usually irreversible because they involve new substances with different molecular structures.

CONCEPT:

Physical and Chemical Changes

• Physical changes involve changes in the state or appearance of a substance without altering its composition.
• Chemical changes involve changes that alter the chemical composition of a substance, resulting in the formation of new substances.

EXPLANATION:

• A Crystallization is a physical change because it involves the transition of a substance from a liquid to a solid state without changing its chemical composition.
• B Photosynthesis is a chemical change because it converts carbon dioxide and water into glucose and oxygen, which involves a change in the chemical composition of the reactants.
• C Ripening of fruit is a chemical change because it involves the conversion of starches to sugars and other chemical changes within the fruit.
• D Formation of curd from milk is a chemical change because it involves the conversion of lactose to lactic acid and alters the chemical composition of milk.

Therefore, the correct answer is 2 B and D.