Some changes are __________ at one time but _________ at another time.
Desirable,Undesirable
Man made, desirable
Slow, undesirable
Fast
___________ is the conversion of a liquid into its vapour state at any temperature below its boiling point.
Evaporation
Boiling
Condensation
None of these
The formation of brown powdery material on the surface of iron in the presence of moisture is called _________.
Rusting
Melting
The changes which repeat themselves at regular intervals of time are called __________ changes.
Periodic
Non periodic
Slow
Periodic change may be used for measuring __________.
Time intervals
Fixed intervals
Prolonged intervals
Burning of fuel is a _________ change but burning of a house is ___________ .
Desirable,undesirable
undesirable, Slow
Both A$B
__________ is the process by which a solute gets dissolved in a solvent.
Dissolution
Evoporation
Sublimation is a ___________ change.
Physical
Chemical
Desirable
_________ is the process in which vapour of a liquid on cooling get converted into the liquid at some fixed temperature.
A change in which only the physical properties of a substance get changed and no new substance is formed is called a __________.
