Changes Around Us: Physical and Chemical

State

Shape

Reactivity with acids

Size

They are made of wood

Sea water contains many salts which speed up rusting

They are always in fresh water

They are not painted

Ripening of fruit

Souring of milk

Dissolving salt in water

Burning of coal

Physical change

Chemical change

Reversible change

None of these

A new substance with a different chemical composition is formed during mixing.

The components can be separated by physical means because no new substance was formed.

The iron filings lose their original magnetic properties after being mixed with sulphur.

The process is a chemical change because the color of the mixture differs from the individual components.

They are generally temporary

New substances are always formed

Only the physical properties change

They are usually reversible

Nitrogen

Carbon dioxide

Oxygen

Argon

The breakdown of ozone into oxygen is a physical change.

Ozone protects us from UV radiation; its breakdown into oxygen is a chemical change.

Ozone is the same as oxygen, so no change occurs.

UV radiation absorbs ozone physically.

Chemical, because you cannot join the pieces back exactly as they were.

Physical, because the chemical composition of the paper remains the same.

Chemical, because the shape has changed permanently.

Physical, because no energy was used.

It is usually reversible.

No new substance is ever formed.

New substances are formed with entirely different properties.

It only involves changes in shape and size.

Water boiling into steam

Ice melting into water

Coal burning into ash

Cutting paper into bits

True, it is a new substance

False, it is the same substance

True, but it is a physical change

False, it has the same properties

Chemical change

Physical change

Irreversible change

Oxidation

Physical change

Chemical change

Reversible change

Periodic change

It is a chemical change because the iodine reacts with starch to form a new chemical complex with a different color.

It is a physical change because the iodine solution only covers the surface of the starch.

It is a physical change because the potato or food item does not change its state of matter.

It is a chemical change because the starch is dissolved by the liquid iodine.

It is a physical change because the sugar simply changed its color.

It is a reversible change because the black substance can be cooled.

It is a chemical change because a new substance with entirely different properties is formed.

It is a physical change because sugar is still present in the black residue.

Oxygen

Carbon dioxide

Hydrogen

Nitrogen

It is definitely a physical change.

It is definitely a chemical change.

It is a reversible physical change.

No conclusion can be drawn.

A physical change in the structure of the food.

Chemical changes leading to the formation of new, smelly substances.

The food simply getting colder.

Evaporation of the water present in the food.

Connecting it to a block of magnesium (sacrificial protection).

Washing it with salt water daily.

Heating the bridge to a very high temperature.

Increasing the oxygen flow around the bridge.

Dry air

Desert areas

Coastal areas

High altitudes

Vinegar

Lime water

Baking soda

Milk of magnesia

It is reversible

No new substance is formed

The chemical composition remains $H_2O$

All of the above

Pure water

Lime water

Salt solution

Sugar solution

The change is only a change in the physical state from liquid to semi-solid.

A new substance with different properties is formed, and the curd cannot be converted back into milk.

The temperature of the milk must remain perfectly constant for the change to occur.

The color of the substance remains white throughout the entire process.

The black solid cannot be separated into iron and sulphur using a magnet.

The sulphur powder simply melts into a liquid and retains its yellow color.

The iron filings can still be easily seen and removed from the final product.

The total mass of the mixture is exactly the same before and after the heating process.

Change A is a physical change and Change B is a chemical change.

Change A is a chemical change and Change B is a physical change.

Both Change A and Change B are chemical changes.

Both Change A and Change B are physical changes.

Both are chemical changes; Process 1 stores energy by forming glucose and $O_{2}$, while Process 2 releases energy and returns $CO_{2}$ and $H_{2}O$ to the environment.

Process 1 is a physical change because it utilizes solar energy to rearrange molecules, while Process 2 is a chemical change because it involves the breakdown of food.

Both are physical changes because they form a cycle in nature where the same $CO_{2}$ and $H_{2}O$ molecules are reused without any permanent chemical transformation.

Process 1 is a chemical change that creates new carbon atoms from sunlight, whereas Process 2 is a physical change that converts those atoms back into energy.

Chemical Reaction

Physical Reaction

Biological Reaction

Nuclear Reaction

To make it look shiny.

To remove the layer of magnesium oxide that may have formed on its surface.

To increase the weight of the ribbon.

To decrease its melting point.

Washing it with fresh water

Painting and using special metal plates

Keeping it out of water

Dipping it in oil

Yes

No

Sometimes

Only in winters

Nitrogen

Hydrogen

Moist air

Carbon dioxide

Make water tasty

Are very flexible

Do not rust easily

Are very cheap

Copper

Aluminium

Chromium and Nickel

Lead

Because it is a gas.

Because it does not stick well to the iron underneath.

Because it is made of oil.

Because iron is a liquid.

Copper

Gold

Zinc

Silver

Waxing a car

Using plastic-coated wire mesh for fences

Storing iron tools in a box with silica gel packets

All of the above

Rust is flaky and non-magnetic, whereas iron is solid and magnetic

Rust is harder than iron

Rust conducts electricity better than iron

Rust is a silvery-grey element

Grease is a chemical that turns iron into zinc

Grease prevents iron's contact with both air and moisture

Grease reacts with oxygen to produce water

Grease makes the iron too slippery for rust to stick

Solid

Liquid

Vapor

None of these

Hydrogen

Carbon dioxide

Oxygen

Helium

Red phosphorus

White phosphorus

Yellow phosphorus

Black phosphorus

Ash

Soot

Water vapor

Oxygen

The process is a physical change because the ribbon only changes its shape into a powder.

The process is a physical change because the white ash can be easily turned back into a magnesium ribbon.

The process is a chemical change because the mass of the ribbon remains identical to the mass of the ash.

The process is a chemical change because the white ash produced is a new substance with properties different from the original metal.

Soot and Oxygen ($O_{2}$)

Carbon monoxide ($CO$) and Hydrogen ($H_{2}$)

Carbon dioxide ($CO_{2}$) and Water vapor ($H_{2}O$)

Nitrogen ($N_{2}$) and Carbon dioxide ($CO_{2}$)

Water is a combustible substance that consumes the oxygen around the paper.

The heat from the flame is conducted to the water, preventing the paper from reaching its ignition temperature.

The ignition temperature of the paper cup increases significantly when it comes into contact with water.

The water reacts chemically with the paper to form a new fireproof substance.

Melting of wax

Stretching a rubber band

Breaking a glass tumbler

Boiling of water

Because trees release more oxygen in summer.

The temperature of the air reaches the ignition temperature of dry grass.

The sun's rays act as a matchstick.

The friction between dry leaves creates enough heat to start a fire.

Calcium carbonate and water are formed.

Calcium oxide and water are formed.

Calcium chloride and hydrogen are formed.

Calcium bicarbonate is formed immediately.

Process A is a physical change and Process B is a chemical change

Process A is a chemical change and Process B is a physical change

Both Process A and Process B are chemical changes

Both Process A and Process B are physical changes

Chemical

Physical

Irreversible

Both physical and irreversible

Physical change

Chemical change

Reversible change

Thermal change

Physical change

Chemical change

Both physical and chemical

None of these

Physical, then Chemical

Chemical, then Physical

Both Physical

Both Chemical

Change in shape

Evolution of a gas

Change in size

Melting

Chemical then Physical

Physical then Chemical

Both Physical

Both Chemical

The absorption of photons by chlorophyll pigments.

The splitting of water into hydrogen and oxygen.

The synthesis of glucose from $CO_2$.

The formation of starch from glucose units.

Tarnishing: Chemical; Polishing: Physical removal.

Tarnishing: Physical; Polishing: Chemical.

Both are chemical changes.

Both are physical changes.

Chlorine reacts with the cellular components of bacteria to destroy them.

Chlorine physically crushes the bacteria.

The bacteria simply move out of the water.

The bacteria change their state from solid to liquid.

It is a permanent change

It is a temporary change

It is a chemical change

It is an irreversible change

Physical change

Chemical change

Reversible change

Periodic change

$Fe$

$O_2$

$Fe_2O_3$

$H_2O$

Melting of butter

Burning of a incense stick (agarbatti)

Boiling of milk

Freezing of juice

The salt can be recovered in its original form by evaporating the water.

The water turns into a new chemical compound when salt is added.

The salt disappears forever and cannot be seen again.

The process of dissolving always results in a permanent chemical reaction.

It is a reversible physical change because the substance is still in the tube.

It is a permanent chemical change because the sugar has decomposed into a new substance.

It is a physical change because only the color changed from white to black.

The sugar has simply melted and will turn back into white crystals upon cooling.

The change in state from liquid to solid is always a physical change.

The change can be reversed by placing the egg in a refrigerator.

A new substance with different properties is formed, and it cannot be turned back into a raw egg.

The shell of the egg remains the same throughout the process.

Procedure 1 is a chemical change because the iron and sulfur are mixed so thoroughly that they cannot be easily separated by hand.

Procedure 2 represents a permanent chemical change because the iron has reacted with sulfur to form a new substance, Iron Sulphide ($FeS$), which no longer possesses the magnetic properties of iron.

Procedure 2 is a physical change because the heat only melts the sulfur, which then coats the iron to hide its magnetic properties from the magnet.

Both procedures are physical changes because the total mass of the iron and sulfur remains the same, proving that no substance was truly changed or lost.

Respiration

Photosynthesis

Combustion

Evaporation

A physical change through evaporation

A chemical change resulting in the formation of a precipitate

A physical change due to temperature increase

No change has occurred

Harmful to us

Useful to us

Always reversible

Always irreversible

Chemical change

Physical change

Biological change

Permanent change

Boiling water

Melting butter

Cooking an egg

Chopping vegetables

To change its weight

To make it a chemical change

To prevent it from coming in contact with oxygen and moisture

To make it conduct electricity

Only physical change

Only chemical change

Both physical and chemical changes

Neither physical nor chemical change

Chemical change

Physical change

Undesirable change

Periodic change

Day and Night

High and Low tides

Forest fire

Heartbeat

Soil erosion due to deforestation.

Ripening of fruits in a warehouse using ethylene gas.

The formation of yogurt from milk.

The glowing of an electric bulb's filament.

Because the chemical composition of the wood remains the same (it is still cellulose and lignin).

Because the change can be reversed by using a very strong glue.

Because no energy was lost or gained during the cutting process.

Because the small pieces can be used to grow a new tree, making it biological.

It acts as a medium that allows the movement of ions and facilitates the reaction between iron and oxygen.

It acts as a catalyst that is never consumed in the reaction.

It physically washes away the iron so oxygen can reach the bottom layer.

It provides the heat necessary for the chemical reaction to start.

Erosion of soil by rain

Construction of a skyscraper

Rusting of a bridge

Growth of a forest

Chemical

Solar

Heat

Nuclear

Breaking of sea waves

Blowing of wind

Ripening of fruits

Melting of snow on mountains

Chemical change

Physical change

Man-made change

Irreversible change

Growth of a tree

Evaporation of a large puddle of water

Ripening of an orange

Digestion of proteins

In a dry garage

In a vacuum chamber

In a humid basement

In a bottle of oil

Very fast chemical change

Extremely slow physical change

Reversible physical change

Biological change

Forest fires

Photosynthesis

Volcanic eruptions

Decomposition of organic matter

Because the concentration of $Cu^{2+}$ ions decreases

Because $FeSO_4$ is blue but less intense

Because the solution becomes acidic

Because the iron nail absorbs the blue pigment

They break apart to form new atoms

They rearrange their spacing and movement but remain chemically identical

They react with atmospheric oxygen to form water vapor

They increase in mass

Magma

Soil

Lava

Crystal

Lichen

Bacteria

Plant roots

Sunlight

Oxidation

Hydrolysis

Expansion

Contraction

Melting

Rubbing

Dissolving

Exploding

Feldspar turning into clay minerals

A rock falling from a cliff and breaking

River water carrying silt

Wind carving a hole in a rock

Carbonation

Frost wedging

Oxidation

Leaching

Oxygen for animals

Minerals and nutrients for soil

Heat for the atmosphere

A way for rocks to grow bigger

It ranks minerals based on how quickly they dissolve in acid

It shows that minerals that form at high temperatures and pressures are the least stable at the Earth's surface

It measures the hardness of minerals

It describes how rocks melt into magma

Weathering can change a hard rock into soft soil

Weathering is essential for releasing nutrients into the soil for plants

Weathering only occurs on the Earth's surface

Weathering is the process that moves rocks from mountains to the sea

Hydrolysis

Carbonation

Frost action (Physical)

Oxidation

Melting of ice

Tearing of paper

Glowing of a bulb

Boiling of water

Chemical change

Physical change

Irreversible change

Periodic change

Very slow change

Very fast change

Chemical change

Reversible change

Chemical change

Physical change

Irreversible change

Biological change

A physical change because the rock is simply changing its shape to fit the water

A physical change because it involves a reversible change in the state of the minerals

A chemical change because new substances with entirely different properties are formed

A chemical change because the total mass of the mountain increases during the process

Physical change, because it only involves a change in the position and speed of the soil particles

Chemical change, because the soil reacts with saltwater to form a new type of land

Physical change, because the solid soil particles are converted into a liquid state

Chemical change, because the soil particles undergo a permanent molecular transformation

Deforestation

Terrace farming

Overgrazing by cattle

Leaving the land fallow

Weathering is physical, erosion is chemical

Weathering is the breaking of rocks; erosion is the movement of the broken pieces

Weathering only happens in summer, erosion in winter

Weathering requires water, erosion requires wind

To prevent the beaker from cracking

To allow large and well-defined crystals to form

To speed up the chemical reaction

To ensure all the water evaporates

It is too expensive

It is too soft and rusts easily

It is too heavy

It cannot be melted