Online Test — Physical and Chemical Changes
25 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 25
In a physical change, the number of new substances formed is:
One
Two
None
Many
Explanation: A physical change forms no new substance; only physical properties change.
Question 2 of 25
Which of the following is a physical change?
Burning of paper
Melting of ice
Rusting of iron
Cooking of food
Explanation: Melting of ice forms no new substance and is reversible, so it is physical.
Question 3 of 25
Most physical changes are:
Irreversible
Reversible
Explosive
Permanent
Explanation: Physical changes can usually be reversed to recover the original substance.
Question 4 of 25
When sugar dissolves in water, the sugar can be recovered by:
Burning
Evaporating the water
Freezing only
Adding acid
Explanation: Evaporating the water leaves the sugar behind, showing dissolving is reversible.
Question 5 of 25
Dissolving salt in water is best described as a:
Chemical change
Physical change
Combustion
Neutralisation
Explanation: No new substance forms and salt can be recovered, so it is a physical change.
Question 6 of 25
In a chemical change, the substances formed are:
The same as before
One or more new substances
Always reversible
Only changed in shape
Explanation: A chemical change forms one or more new substances with new properties.
Question 7 of 25
A chemical change is also called a:
Physical change
Chemical reaction
State change
Mixture
Explanation: Because new substances form, a chemical change is also called a chemical reaction.
Question 8 of 25
Chemical changes are usually:
Easily reversible
Irreversible
Only physical
Temporary
Explanation: New substances form that cannot easily be turned back, so they are usually irreversible.
Question 9 of 25
Which of the following is a chemical change?
Melting of butter
Souring of milk into curd
Tearing of paper
Dissolving sugar
Explanation: Souring of milk forms a new substance (curd) and is irreversible, so it is chemical.
Question 10 of 25
Burning of fuel gives out energy mainly in the form of:
Heat and light
Sound only
No energy
Magnetism
Explanation: Burning releases energy as heat and light, a sign of a chemical change.
Question 11 of 25
The bubbling seen when baking soda is added to vinegar is a sign called:
Change in colour
Evolution of a gas
Formation of a precipitate
Change in shape
Explanation: The bubbles are a gas released during the reaction — evolution of a gas.
Question 12 of 25
An insoluble solid that appears when two solutions are mixed is called a:
Solution
Precipitate
Mixture
Gas
Explanation: A precipitate is a new insoluble solid that signals a chemical change.
Question 13 of 25
The browning of a freshly cut apple is a sign of chemical change known as a:
Change in colour
Gas evolution
Temperature change
State change
Explanation: The apple changing to brown is a change in colour, a sign of a chemical change.
Question 14 of 25
A reaction that makes its container feel warm shows a sign of chemical change called a:
Change in smell
Change in temperature
Precipitate
Colour change
Explanation: Heat given out warms the mixture — a change in temperature.
Question 15 of 25
Which of the following is NOT necessarily a sign of a chemical change?
Formation of a precipitate
Evolution of a gas
Bubbles from boiling water
Change in colour
Explanation: Boiling water bubbles are only vapour with no new substance, so not a chemical change.
Question 16 of 25
Rusting of iron requires the presence of:
Water only
Oxygen only
Both water and oxygen
Neither water nor oxygen
Explanation: Iron rusts only when both moisture (water) and oxygen (air) are present together.
Question 17 of 25
Rusting of iron is an example of a:
Physical change
Chemical change
Change of state
Reversible change
Explanation: Rust is a new substance, so rusting is a chemical change.
Question 18 of 25
Coating iron with a layer of zinc to prevent rusting is called:
Painting
Galvanisation
Crystallisation
Neutralisation
Explanation: Galvanisation is coating iron with zinc to protect it from rusting.
Question 19 of 25
Iron objects rust faster in areas that are:
Dry and cold
Humid and coastal
Sealed and airless
Free of moisture
Explanation: Humid, salty coastal air provides moisture that speeds up rusting.
Question 20 of 25
A rust-resistant alloy used for cutlery is:
Pure iron
Stainless steel
Copper
Lead
Explanation: Stainless steel is an iron alloy that resists rusting, ideal for cutlery.
Question 21 of 25
Crystallisation is used to obtain pure ______ of a substance from its solution.
Gases
Crystals
Liquids
Mixtures
Explanation: Crystallisation produces pure, well-shaped crystals from a solution.
Question 22 of 25
Crystallisation is an example of a:
Chemical change
Physical change
Irreversible change
Combustion
Explanation: The substance stays chemically the same, so crystallisation is a physical change.
Question 23 of 25
To obtain large, well-formed crystals, a hot saturated solution should be:
Cooled slowly
Cooled quickly
Boiled again
Frozen instantly
Explanation: Slow cooling gives time for large, well-formed crystals to grow.
Question 24 of 25
During crystallisation, impurities mostly:
Form the crystals
Remain in the liquid
Disappear completely
Turn into gas
Explanation: Pure crystals separate out while impurities stay dissolved in the liquid.
Question 25 of 25
Common salt is obtained from seawater by:
Galvanisation
Evaporation (crystallisation)
Neutralisation
Rusting
Explanation: Evaporating seawater leaves salt crystals behind, a form of crystallisation.