Dissolution of common salt is a ________ change.
Physical
Chemical
Non periodic
None of these
Sublimation is a ___________ change.
Desirable
The changes which repeat themselves at regular intervals of time are called __________ changes.
Periodic
Fast
Slow
Tooth decay is an example of a _________ change.
Undesirable
Some changes are __________ at one time but _________ at another time.
Desirable, Undesirable
Man made, desirable
Slow, undesirable
Name the one which happens slowly.
Magnesium ribbon is burnt
Explosion of a fire cracker
Rusting of iron
Paper burns
Which of these statements is FALSE?
A reversible reaction produces new materials.
Chemical changes are usually irreversible.
Physical changes are usually reversible.
Pick the odd one out.
Rain fall
Construction of roads
Change of day and night
Flood
Curdling of milk is __________ reaction.
Endothermic
Exothermic
Both A&B
