Olympiad Science - Physical and Chemical Changes
Exam Duration: 45 Mins Total Questions : 30
What kind of change does a glowing electric bulb undergo?
- (a)
Physical change
- (b)
Chemical change
- (c)
Irreversible change
- (d)
Undesirable change
As no new substance is formed when an electric bulb glows, it is a physical change.
Study the reaction given below
What kind of a change takes place in the given reaction?
- (a)
Chemical change
- (b)
Physical change
- (c)
Biochemical
- (d)
Both (A) and (B)
When a piece of iron is dipped in copper sulphate solution, iron sulphate is formed. This is a chemical reaction in which iron replaces copper to form iron sulphate.
Fe(s) + CuSO4(aq) ➝ FeSO4(aq) + Cu(s)
What kind of change is undergone when wheat flour is made into a chapati?
- (a)
Physical change.
- (b)
Reversible, chemical change.
- (c)
Irreversible, chemical change.
- (d)
Change of state.
An· irreversible, chemical change is undergone by wheat flour in the preparation of chapathies.
Which of the following is a chemical change?
- (a)
Food gives out a foul smell
- (b)
Pollution of air caused due to explosion of fireworks
- (c)
Change of colour in a cut apple, if left outside
- (d)
All of the above
Statements (A), (B) and (C) are examples of chemical change.
Pooja took a candle in a vessel and heated the vessel. Even though the candle did not burn, it changed its shape and state. What kind of change is this?
- (a)
Neutralisation
- (b)
Physical change
- (c)
Chemical change
- (d)
Irreversible change
The candle melted on heating but no new substance is formed. So, it is a physical change.
What kind of change does sodium chloride undergo when it is added to water?
- (a)
Physical change
- (b)
Chemical change
- (c)
Chemical reaction
- (d)
Temporary change
When sodium chloride is added to water, there is no change in molecular composition. Hence, it is a physical change.
Match the entries in Column-I with those in Column-II.
- (a)
a-2, b-3, c-4, d-t
- (b)
a-4, b-3, c-2, d-t
- (c)
a-4, b-3, c-1, d-2
- (d)
a-3, b-4, c-2, d-l
Burning of wood - chemical change
Formation of day and night - periodic change.
Curdling of milk - slow change
Melting of ice - physical change
The correct combination is a-4, b-3, c-2, d-1
Which of the following isa physical change?
- (a)
Grinding of wheat
- (b)
Photosynthesis
- (c)
Curdling of milk
- (d)
Burning of coal
During grinding of wheat, only the size changes.The grains of wheat are powdered to flour. Hence, it is only a physical change.
Which of the following properties of iron is NOT a physical property?
- (a)
Electrical conductivity
- (b)
Magnetic property
- (c)
Good conductor of heat
- (d)
Reaction with moisture to get rusted
Rusting is not a physical property as the rust of iron is a new substance, an oxide of iron.
What kind of change is undergone by the expansion of railway tracks during summer?
- (a)
Irreversible, physical change
- (b)
Reversible, physical change
- (c)
Irreversible, chemical change
- (d)
Reversible, chemical change
The railway tracks undergo expansion in summer and contraction in winter. So, it is a reversible, physical change
Which of the following is NOT a physical change?
- (a)
Tearing a paper
- (b)
Heating an iron rod to bend it
- (c)
Freezing water into ice
- (d)
Growth of a sapling into a tree
Tearing a paper, bending an iron rod after heating and freezing water into ice in all these changes we do not observe the formation of any new substances. Hence, all are physical changes.
What kind of change is neutralisation?
- (a)
A physical change
- (b)
A chemical change
- (c)
Sometimes a physical and sometimes a chemical change
- (d)
Neither a physical nor a chemical change
Neutralisation is a chemical change in which an acid reacts with a base to form salt and water.
Which of the following is a chemical change?
- (a)
Cooking of food
- (b)
Evaporation of water
- (c)
Mowing of grass
- (d)
Melting of wax
Cooking of food leads to the formation of a new substance and also- the change is permanent. Therefore, it is a chemical change.
Which of the following is NOTa chemical change?
- (a)
Respiration
- (b)
Crystallization
- (c)
Combustion
- (d)
Oxidation
The formation of large crystals of pure substances from their solutions is called crystallization. It is a physical change.
What kind of change is undergone by the burning of wax?
- (a)
Physical change
- (b)
Chemical change
- (c)
Reversible change
- (d)
Periodic change
Melting of wax is a physical change, but burning of wax is a chemical change as it results in the formation of new substances, CO2 and water vapour.
Which of the following is an irreversible change?
- (a)
Change of water into steam
- (b)
Melting of wax
- (c)
Transpiration
- (d)
Corrosion
Corrosion is a chemical change, and it is irreversible
When a substance undergoes a physical change, what change is seen in its mass?
- (a)
It increases.
- (b)
It decreases.
- (c)
It remains the same.
- (d)
It either increases or decreases.
During a physical change, no new substance is formed. Hence, there is no change in the mass of the substance
Which of the following is a chemical change?
- (a)
Explosion of crackers
- (b)
Magnetisation of iron
- (c)
Charging of a battery
- (d)
Both (B) and (C)
Explosion of crackers is a chemical change as it results in the formation of new substances and it is irreversible.
Which of the following is a physical change?
- (a)
The rusting of iron nails
- (b)
The burning of diesel
- (c)
Breaking of a glass bottle
- (d)
The heating of iron with sulphur
A glass bottle after it breaks undergoes change only in the size and shape, but not in its composition. So, it is a physical change.
Which of the following changes caused by heating a substance is irreversible?
- (a)
Change in size
- (b)
Change in state
- (c)
Change in colour
- (d)
Change in substance
Changes given in (A), (B) and (C) are reversible. However, change in a substance due to heating may not be reversible. For example, when paper is burnt, ash is formed. Ash is a new substance and this change is irreversible.
What change is observed when a piece of magnesium wire is burnt?
- (a)
Physical change
- (b)
Chemical change
- (c)
Nuclear change
- (d)
Both (A) and (B)
During the burning of magnesium wire, magnesium reacts with oxygen to form magnesium oxide,a new substance. Hence, it is a chemical change.
Observe the following figures.
Identify the type of change.
- (a)
Physical change
- (b)
Chemical change
- (c)
Reversible change
- (d)
Periodic change
In the given figure, carbon reacts with oxygen to form carbon dioxide, a new substance. It is a chemical change
Which of the following suffers maximum damage due to the rusting of iron?
- (a)
2
- (b)
1
- (c)
3
- (d)
4
Lower part of ship (made up of iron) always remains under water. The salt water makes the process of rust formation faster. So, a ship undergoes rusting faster than the others.
Read the following statements carefully and then select the correct answer.
- (a)
Both the statements 1 and 2 indicate physical changes.
- (b)
Both the statements 1 and 2 indicate chemical changes.
- (c)
Statement 1 shows a physical change while statement 2 shows a chemical change.
- (d)
Statement 1 shows a chemical change while statement 2 shows a physical change.
1st change is reversible. When the iron ball cools down, it will again pass through the ring. It is a physical change. 2nd change is irreversible aswe cannot get back the same seed once it has started to grow. Hence, it is a chemical change.
What change takes place when a boy kicks a football?
- (a)
Exothermic reaction
- (b)
Endothermic reaction
- (c)
Physical change
- (d)
Chemical change
The kicking of a ball by the player is an example of a physical change.
Three substances given below are kept in the open for a few days.
Which of them will undergo a chemical change?
- (a)
Eggs
- (b)
Plastic bottle
- (c)
Both eggs and moth balls
- (d)
Eggs, plastic bottle and moth balls
(i) The bacteria present in air break down the proteins in the egg whites and hydrogen sulphide gas is produced which gives a 'rotten egg' smell. As the change is permanent and irreversible, it is a chemical change.
(ii) Plastic bottle does not show any change.
(iii) The moth balls(naphthalene) sublime at room temperature. It is a physical change.
Karuna wrapped some green gram pulses in a wet cotton cloth and when she observed them after a couple of days, she found small white growths on them. What could be this change?
- (a)
Physical change
- (b)
Temporary change
- (c)
Chemical change
- (d)
Periodic change
Pulses germinate undergoing several changes. During the chemical change, physical changes also takes place. The change is irreversible. Hence,it is a chemical change.
On sprinkling salt on an ice cube, it starts melting. What change does the cube of ice undergo?
- (a)
Physical change
- (b)
Chemical change
- (c)
Molecular change
- (d)
Permanent change
On sprinkling salt on a piece of ice,it melts. It is a physical change (a temporary change).
Which of the following changes does food in a refrigerator undergo?
- (a)
Slow, physical change
- (b)
Slow, chemical change
- (c)
Fast, chemical change
- (d)
Fast, physical change
Low temperature in a fridge slows down the chemical change in food and keeps it fresh for a long time
Which of the following changes results in the formation of a new substance?
- (a)
Physical
- (b)
Reversible
- (c)
Chemical
- (d)
Periodic
A chemical change results in the formation of a new substance