Winnowing is useful only when
Two solids have different melting points
Two solids have different boiling points
Two solids have different magnetic properties
Two solids have different weights
Which of the following property is not considered when the components of a mixture is separated ?
Density
Energy - change
Volatile nature
Boiling point
A pure substance is made up of
Only one kind of molecules
Two or more kinds of molecules
Different types of molecules
None
Pure substances possess
Variable melting points and boiling points
Nonuniform
Variable properties
Fixed melting points and boiling points
The following property is used to find the purity of a substance
Specific gravity
Volume
Temperature
Mass
The process by which a solid changes directly into gas is called
Decantation
Sublimation
Condensation
Sedimentation
We separate mixtures to
Remove unwanted components
To get pure substances
Both the above
None of these
Choose the substance that shows sublimation
Napthalene
Toluene
Kerosene
Water
To separate a mixture of two or more gases ______ method is used.
Liquification
Distillation
Which of the following mixtures will be the most difficult to separate ?
Iron filings + sand
Sand + water
Saw dust + stones
Nitrogen + hydrogen
