Which of the following are not physical changes?
Which of the following are not physical changes?
The correct option is C Electrolysis of water
Physical change: A physical change occurs when some of the material’s physical characteristics change but the matter’s chemical properties do not. Physical changes of two types: reversible and irreversible. Melting is a reversible physical change in which the melted ice cube can be frozen again.
Chemical change: A chemical change results in a new product. The physical and chemical properties of the new substance so formed also change. During a chemical change, the molecular bonds break, and the composition and properties of the substance change. Chemical change results in the breaking and making of bonds.
An explanation for the correct option:
Option (C)
Electrolysis of water: Electrolysis of water refers to the breaking of water into its constituent elements hydrogen and oxygen when supplied with electricity. It is a chemical process in which the conversion of water to hydrogen and oxygen takes place. At the same time when hydrogen and oxygen are kept together, they will not form the water. It is irreversible. There is the breaking of chemical bonds and the formation of new bonds is taking place. That is why it is a chemical change.
An explanation for the incorrect options:
Option (A)
Melting of ice: Melting of ice is a physical change in which no new substance is formed. Melted ice can be frozen again.
Option (B)
Burning of candle: In a burning candle, wax gets converted from solid into a liquid. This is a physical change (as it is a change in the state of matter, no new substance is formed, no change in chemical properties and can be reversed) The burning of wax near the flame burns and convert into carbon dioxide which cannot be again converted to wax, so this is a chemical change.
Option (D)
Evaporation of water: Evaporation water refers to the change of water (liquid) into vapor (gaseous state). It is a physical change as the evaporated water can be obtained again by the process of condensation (gas to liquid).
Thus, the correct answer is an option (C)
Electrolysis of water
Physical change: A physical change occurs when some of the material’s physical characteristics change but the matter’s chemical properties do not. Physical changes of two types: reversible and irreversible. Melting is a reversible physical change in which the melted ice cube can be frozen again.
Chemical change: A chemical change results in a new product. The physical and chemical properties of the new substance so formed also change. During a chemical change, the molecular bonds break, and the composition and properties of the substance change. Chemical change results in the breaking and making of bonds.
An explanation for the correct option:
Option (C)
Electrolysis of water: Electrolysis of water refers to the breaking of water into its constituent elements hydrogen and oxygen when supplied with electricity. It is a chemical process in which the conversion of water to hydrogen and oxygen takes place. At the same time when hydrogen and oxygen are kept together, they will not form the water. It is irreversible. There is the breaking of chemical bonds and the formation of new bonds is taking place. That is why it is a chemical change.
An explanation for the incorrect options:
Option (A)
Melting of ice: Melting of ice is a physical change in which no new substance is formed. Melted ice can be frozen again.
Option (B)
Burning of candle: In a burning candle, wax gets converted from solid into a liquid. This is a physical change (as it is a change in the state of matter, no new substance is formed, no change in chemical properties and can be reversed) The burning of wax near the flame burns and convert into carbon dioxide which cannot be again converted to wax, so this is a chemical change.
Option (D)
Evaporation of water: Evaporation water refers to the change of water (liquid) into vapor (gaseous state). It is a physical change as the evaporated water can be obtained again by the process of condensation (gas to liquid).
Thus, the correct answer is an option (C)
