We keep food at low temperature in a refrigerator because it:
Saves money
Makes food more tastier
Kills bacteria present in the food
In fashionable to keep the food in the refrigerator
Burning of Magnesium ribbon is a ________ change.
Physical
Chemical
Reversible
Temporary
A change in which a substance undergoes a change in its physical properties is called a ________ change.
Thermal
Thermodynamic
The cells used in a wrist watch undergo:
Physical change
Periodic change
Chemical change
None of these
Cooking of rice is an example of:
Irreversible change
Endothermic reaction
Both A and B
The formation of rust on the surface of iron is called __________ of iron.
rusting
melting
condensation
none of these
The process of depositing a layer of zinc on iron is called
Galvanization
Vulcanization
Polymerization
Condensation
Chemical changes are
temporary
partial
permanent
__________ turns lime water milky.
Oxygen
Carbondioxide
Hydrogen
Carbonmonoxide
A chemical reaction in which energy is liberated is called:
Exothermic reaction
Photo chemical reaction
