Breaking of a glass plate is an example of a physical change.
True
False
Evaporation of water is a physical change which is man-made and undesirable.
True
False
Freezing is a process in which a substance changes from the liquid state to the solid state on cooling.
True
False
Naphthalene sublimes at room temperature.
True
False
A chemical change is permanent and reversible.
True
False
Baking a chapati is a chemical change.
True
False
Boiling of water is a physical change in which energy is released in the form of heat.
True
False
Combustion is a chemical change that involves release of energy.
True
False
Click the correct answer.
Which of the following changes occur after a regular interval of time?
Periodic changes
Desirable changes
Slow changes
Reversible changes
Which of the following is a process in which a solid, liquid or gas mixes uniformly with another substance to form a solution?
Evaporation
Boiling
Freezing
Dissolving
Which of the following is a process by which a substance changes directly from the solid state to the gaseous state without forming the liquid state?
Evaporation
Sublimation
Freezing
Dissolving
Which of the following is a process by which iron objects when left exposed to moist air develop a brown flaky layer of hydrated iron oxide on their surface?
Rusting
Combustion
Sublimation
Fermentation
Which of the following is a process by which a substance changes from the solid state to the liquid state on heating?
Evaporation
Melting
Freezing
Dissolving
Click each box on the left and then click the matching box on the right.
Match the columns by dragging
Periodic changes
Fast changes
Chemical change
Rust
Fermentation
Changes after a regular interval of time
Changes occurring very quickly
Release of heat and carbon dioxide
A dull brittle brown substance
Change in composition of a substance
Click the correct answer.
Changes that occur on their own, i.e., without any human effort are called
.
unnatural changes
man-made changes
natural changes
serial changes
Changes that occur very quickly are called
changes.
slow
desirable
undesirable
fast
The revolution of the earth is a
change.
man-made
natural
reversible
irreversible
A
refers to the transformation of a substance from one form to another.
change
reaction
action
reflex
Changes that are not desirable to us are called
.
natural changes
undesirable changes
desirable changes
reversible changes
A
change is temporary and reversible.
chemical
physical
man-made
natural
There is an exchange of
during a chemical change.
chemicals
energy
quality
quantity
The process by which a substance is broken down by the action of microorganisms with the release of heat and carbon dioxide is called
.
fragmentation
fermentation
burning
cooking
are the changes in which we get back the initial substance by reversing the action.
