What new materials are formed when a candle burns?
Melted wax
Water and carbon dioxide and soot
No new materials are formed
None of these
Periodic changes takes place repeatedly after a certain _________ of time.
Fixed interval
Unfixed interval
Both A&B
From the below changes which change gives us harmful effects?
Flood
Ripening of fruits
Fermentation of rice dough
Decaying of organic wastes into organic manure
The change which can be reversed by changing the condition is known as ________ change.
Reversible
Irreversible
Endothermic
Which of these statements is FALSE?
A reversible reaction produces new materials.
Chemical changes are usually irreversible.
Physical changes are usually reversible.
Why is nothing left behind when distilled water is evaporated?
Because nothing was dissolved in it
Because anything that was dissolved has evaporated
Because nothing can dissolve in water
Which substance can dissolve completely in water?
Sand
Flour
Salt
The changes which are brought and controlled by man is called:
Natural
Man made
Chemical
Physical
The changes that occur in nature on their own are called:
Name the one which happens slowly.
Magnesium ribbon is burnt
Explosion of a fire cracker
Rusting of iron
Paper burns
