Which of the following is an example of a Chemical and Physical change?

A physical change is a change that occurs when a substance undergoes change but doesn’t alter the chemical composition. No new substance formed in physical changes and it only changes the appearance of the substance. It is reversible and only a temporary change.

Examples of Physical changes –

• Ice melting into water
• Mixing salt and sand
• Water freezing
• Pouring water into a glass
• Grinding pepper
• Chopping wood
• Cracking an egg
• Melting candle wax

A chemical change is a change that alters the chemical composition of a substance and because of this, a new substance is formed with distinct properties. It is mainly irreversible change i.e. original substance cannot be obtained by simple physical means. A chemical change affects both the physical and chemical properties of a substance.

Examples of  Chemical changes –

• Wood burning in a fireplace
• Digesting a hot dog
• Milk souring
• Frying an egg
• Photosynthesis reaction
• Rusting of iron
• Paper burning
• Waste decomposition
• Rotting of food
• Acid-base reactions
• Firework explosions

Physical Change vs Chemical Change
In a physical change, no chemical reaction occurs and chemical composition remains the same	In a chemical change, a chemical reaction occurs, and the chemical composition is changed
A new substance is not formed in a physical change	A new substance is formed in a chemical change
It is temporary and reversible in nature	It is irreversible and changes are mostly permanent
It only changes the appearance of the substances	It changes both the physical and chemical properties of the substance
It involves very little to no absorption of energy	Absorption and the evolution of energy take place
Examples of Physical changes – Chopping vegetables, Breaking a glass, Sublimation of dry ice, Melting ice, Cutting fabric, etc.	Examples of Chemical changes – Fruit ripening, Burning firewood, Fireworks, Metabolism, Electroplating, etc.

Let’s understand “Physical Change Vs Chemical Change” with the help of various examples and explanations.

Q.1 Which of the following is an example of chemical change?

(a). Burning of the candle

(b). Cooking of food

(c). Freezing of water

(d). Rusting of iron

(e). Digestion of food

(f). Growth of plant

(g). Mixing of iron filling and sand

Answer = Option (a), (b), (d), (e), (f)

Burning of the candle, Cooking of food, Rusting of iron, Digestion of food, Growth of plants are examples of chemical changes, and Freezing of water, Mixing of iron filling with sand are examples of physical changes in the given list of the above question.

Explanation:-

(a). Why the burning of a candle is a chemical change? 

When the candle is burned, the atmospheric air reacts with the hydrogen and carbon of the candle wax, hence, producing CO₂ (a new substance). During this process, most of the candle wax is burned and we cannot reverse it. Hence, the burning of a candle is a chemical change.

(b). Why the cooking of food is a chemical change? 

When the food is cooked at an elevated temperature, the internal composition of the food is broken down resulting in the formation of a new substance. As we know, raw vegetables cannot be reverted back once cooked, hence, the cooking of food is a chemical phenomenon.

(c). Why is the freezing of water a physical change?

When the water is freezing then it converts into solidified ice but we can change this solidified ice again into the water by heating it, hence, the freezing of water is a physical change.

(d). Why the rusting of iron is a chemical phenomenon?

During rusting of iron, the Fe undergoes an oxidation process and changed into a new substance which is called iron oxide(Fe₂O₃), this process cannot be reversed, hence, the rusting of iron is a chemical change.

(e). Why is the digestion of food a chemical phenomenon? 

The larger macromolecules present in food are broken down into simpler molecules with the help of enzymes present in the stomach during the food digestion process and in this process, a new chemical substance is formed, hence, it is a chemical phenomenon.

(f). Why the growth of plants is a chemical phenomenon? 

“Growth of plant is a chemical change because it involves photosynthesis reaction, and many other chemical reactions too.” When the plant takes growth, its shape and size also increase which cannot be reverted back.

(g). Why is the mixing of iron filling and sand a physical change? 

This is because when the iron filling and sand are mixed then they can easily be separated using the magnet, hence, the mixing of iron filling and sand can revert back to its original form, hence, it is a physical change.

Q.2 Which of the following is not a physical change?

(a). Burning of wood

(b). Water converting into steam

(c). Breaking of a brick

(d). Melting of ice

(e). Boiling of water

Answer = Option (a)

The burning of wood is a chemical change whereas all other options (b, c, d, e) are physical changes.

Explanation:-

(a). Why the burning of wood is a chemical process? 

When the wood is burned, it changes into a new substance like ash, heat, CO₂ gas, etc. that cannot be reverted back, hence, the burning of wood is a chemical phenomenon.

(b). Why is the water converting into steam a physical change? 

The chemical composition of steam and water remains the same, hence, it is a physical phenomenon.

(c). Why is the breaking of a brick a physical change? 

When the brick is broken then it doesn’t turn into a new substance as there is no effect on its internal structure, hence, it is a physical change.

(d). Why is the melting of ice a physical change? 

When the ice is melting then it turns into water(liquid). Both ice and water are made up of hydrogen and oxygen atoms, hence, the molecule composition of water and ice is still the same, which means, they are interlinked with the physical phenomenon.

(e). Why is the boiling of water a physical change?

When the water is boiled it turns into water vapor. The molecular structure or chemical composition of water vapor and liquid water are the same, hence, there is no new substance is formed.

Q.3 Which of the following is not an example of physical change?

(a). Evaporation of liquid

(b). Moving of a wheel

(c). Condensation of steam

(d). Explosion of dynamite

Answer = Option (d)

The explosion of dynamite is a chemical change whereas all other options (a, b, c) are physical changes.

Explanation:-

(a). Why is the evaporation of the water a physical change? 

When the water in the liquid state is evaporated it turns into water vapor (gaseous state), still, it is water, and only physical appearance is changed.

(b). Why is the moving of the wheel a physical change?

The moving of the wheel is not causing any formation of a new substance, hence, it is a physical phenomenon.

(c). Why is the condensation of steam a physical change? 

The condensation of steam is a physical process as no new substance is formed and the molecular or chemical composition of steam is the same.

(d). Why the explosion of dynamite is a chemical phenomenon? 

The explosion of dynamite involves a release of a high amount of energy and the formation of new substances like carbon dioxide and carbon monoxide, hence, it is a chemical change.

Q.4 Which of the following is an example of chemical change?

(a). Burning of methane

(b). Sublimation of camphor or iodine

(c). Evaporation of seawater to get salt

(d). Melting of sodium in a nuclear reactor

Answer = Option (a)

The burning of methane is a chemical change whereas all other options (b, c, d,) are physical changes.

Explanation:-

(a). Why the burning of methane is a chemical phenomenon? 

When the methane is burned down, it produces CO₂, water, and energy(new substances), hence, the burning of methane is a chemical phenomenon.

(b). Why is the sublimation of camphor or iodine a physical change? 

The sublimation process involves the change of state which is a physical phenomenon.

(c). Why is the evaporation of seawater to get salt a physical change? 

The evaporation of seawater to get salt is just a change in the physical state of water from liquid to gas.

(d). Why is the melting of sodium in a nuclear reactor a physical change?

This is because melting is not a chemical reaction phenomenon, in the melting process, the changes occur in only the properties of substances.

Q.5 Which of the following is a physical change?

(a). Digestion of food

(b). Dissolving sugar in water

(c). Burning of coal

(d). Photosynthesis

Answer = Option (b)

Dissolving sugar in water is a physical change while Burning coal, photosynthesis, and Digestion of food are examples of chemical changes.

Explanation:-

(a). Why is the digestion of food a chemical change? 

When we digested food, our body mechanism starts breaking the macromolecule into simpler molecules with the help of enzymes. This process alters the chemical structure of food and we get a new substance that cannot be reversed, hence, the digestion of food is a chemical phenomenon.

(b). Why is the dissolving sugar in the water a physical change? 

It is obvious that no new substance is formed when we dissolve sugar in water, only, a mixture is formed that can easily be separated by vaporization followed by condensation and crystallization.

Hence, no chemical composition is changed, and easily reversible making the dissolving sugar in the water a physical change.

(c). Why is the burning of coal a chemical change?

“Coal is made up of carbon and hydrocarbons, which contain energy that can be released through combustion”. When the coal is burned, the carbon is converted into CO₂ and hydrogen into water. Hence, new substances are formed that cannot be reversed, therefore, the burning of coal is a chemical change.

(d). Why photosynthesis is a chemical change?

In the photosynthesis process, a chemical reaction is involved (Water + CO₂ → glucose + O₂). The formation of new chemical species and the involvement of endothermic reactions make photosynthesis a chemical phenomenon.

Q.6 Which of the following are physical changes?

(a). Drawing a wire of iron metal

(b). Melting of iron metal

(c). Bending of an iron rod

(d). Rusting of iron

Answer = Option (a), (b), (c)

The Drawing of a wire of iron metal, the Melting of iron metal, and the Bending of an iron rod are examples of physical change whereas the Rusting of iron is an example of chemical change.

Explanation:-

(a). Why is the drawing of a wire of iron metal, not a chemical change? 

Drawing a wire of iron metal means converting iron metal into thin wire, hence, only the physical appearance of iron metal is changed, hence, it is a physical phenomenon.

(b). Why the melting of iron metal is not a chemical change? 

The melting of iron metal is a physical phenomenon because melting involves the changing of matter from a solid to a liquid state, there is no effect on the chemical composition or properties.

(c). Why is the bending of an iron rod a physical process? 

Now, this is common sense, when we bend the iron rod, only the physical appearance of the iron rod is changed from straight to circular or in another shape. But the chemical composition remains the same.

(d). Why is the rusting of iron a chemical change? 

During rusting of iron, the Fe undergoes an oxidation process and changed into a new substance which is called iron oxide(Fe₂O₃), this process cannot be reversed, hence, the rusting of iron is a chemical change.

Q.7 Which of the following is not an example of chemical change?

(a). Cooking of food

(b). Curdling of milk

(c). Burning of a candle

(d). Magnetization of iron

Answer = Option (d)

The Magnetization of iron is an example of physical change while the rest are chemical changes.

Explanation:-

(a). Why is the cooking of food a chemical change? 

As we know, raw vegetables cannot be reverted back once it cooked, hence, the cooking of food is a chemical phenomenon.

(b). Why is the curdling of milk a chemical phenomenon?

When the milk is changed into curd then the change is permanent in nature as milk loses its chemical properties and distorted the internal structure. Hence, the curdling of milk is a chemical change.

(c). Why is the burning of a candle a chemical phenomenon? 

When the candle is burned, the atmospheric air reacts with the hydrogen and carbon of the candle wax, hence, producing CO₂ (a new substance). During this process, most of the candle wax is burned and we cannot reverse it. Hence, the burning of a candle is a chemical change.

(d). Why the magnetization of iron is a physical change? 

There is no chemical process or reaction involved in the process of magnetization of iron, also, when demagnetizes the iron then it loses all magnetic power, hence, a reversible process is possible, therefore, this makes the magnetization of iron a physical process.

Q.8 Which of the following is an example of physical change?

(a). Burning oil

(b). Tarnishing of silverware

(c). Electrolysis of water to hydrogen gas and oxygen gas

(d). Boiling water

Answer = Option (d)

The boiling water is a physical change whereas all other options (a, b, c) are chemical changes.

Explanation:-

(a). Why is burning oil a chemical phenomenon? 

The combustion reaction occurs in the burning oil process that changes its internal composition and a new substance is formed, hence, it is a chemical change.

(b). Why the tarnishing of silverware is a chemical change? 

The tarnishing of silver changes silver to silver sulfide, hence, the chemical composition or properties is changed that cannot be reverted back by simple physical means.

(c). Why the electrolysis of water to hydrogen and oxygen gas is a chemical change? 

The chemical properties of H₂O are changed after the electrolysis process and a new substance is formed(hydrogen and oxygen gas), hence, it is a chemical phenomenon.

(d). Why boiling water is a physical change?

When the water is boiled it turns into water vapor. The molecular structure of water vapor and liquid water are the same, there is no new substance is formed. Hence, the boiling of water is a physical process.

FAQ

How is a Chemical change different from a Physical change?

Chemical changes alter the chemical composition of a substance and form a new substance with different properties whereas physical changes don’t affect the chemical composition or chemical properties of a substance. A physical change only affects physical properties like shape, size, color, melting point, boiling point, etc.

Is Fermentation an example of chemical or physical change?

“Fermentation is a chemical process in which molecules such as glucose are broken down anaerobically.” When the fermentation of milk is done then a new substance is formed that is curd. Hence, the curd cannot be reverted back to its original form(milk). Hence, the fermentation process is an example of chemical change.

Which of these is a chemical change “Boiling an egg” or Boiling of water?

Boiling an egg is an example of chemical change whereas boiling water is an example of physical change. When the egg is boiled at an elevated temperature then a distortion happens in the internal structure of the egg that causes a change in its molecular structure. When the water is boiled it turns into water vapor. The molecular structure of water vapor and liquid water are the same, hence, there is no new substance is formed.

Is Milk souring an example of physical or chemical change?

No, milk souring is an example of chemical change.

Which of these is an example of physical change “Wood burning in a fireplace” or “Chopping wood for a fire”?

Wood burning in a fireplace is an example of chemical change as when the wood is burned, the presence of heat and oxygen transforms it into ash, water, CO2, and vapors, hence, the new substance is formed. Whereas chopping wood for a fire is an example of a physical change as when the wood is chopped into smaller pieces, it remains the same throughout the chemical composition, only, the physical appearance of wood is changed.

Summary

• Physical vs Chemical change: When a substance undergoes change without changing the chemical composition is referred to as a Physical change whereas when a substance undergoes a change that changed the entire molecular or chemical composition and forms a new substance referred to as a Chemical change.
• Examples of physical change – Are water freezing, Boiling water, Melting wax, Pouring water into a glass, Chopping wood into a pieces, Sanding wood, Bending the wire, Shredding paper, Cutting your hair, Rock erosion, etc.
• Examples of Chemical change – Burning of wood, Frying an egg, Waste decomposition, Rusting of iron, fireworks explosions, Mixing acid and base, Burning a candle, Electroplating a metal, Milk souring, Chemical battery reactions, etc.
• Physical change vs Chemical change: Physical change is a temporary change and is reversible in nature whereas Chemical change is a permanent change and it is mostly irreversible i.e. Generally, it cannot return to its original state by simple physical means.
• There is no new substance formed in physical change whereas, in chemical change, a new substance is formed because of the changing of molecular composition or chemical composition.