The process by which a solid changes directly into gas is called :
decantation
sublimation
condensation
sedimentation
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
A pure substance is made up of :
only one kind of molecules
two or more kinds of molecules
different types of molecules
none of the above
Which of the following mixtures will be the most difficult do separate ?
Iron fillings + sand
Sand + water
Saw dust + stones
Nitrogen + hydrogen
In a mixture , constituents exhibit :
similar properties
only those properties which are characteristic to the mixture
their own properties
no properties
A few coloured glass pieces that are big in size are mixed with sugar . The easiest way to separate them is :
heat the mixture
add the mixture of water
handpick the glass pieces
handpick the sugar particles
Identify the mixture from the following.
Oxygen
Carbon dioxide
Hydrogen
Air
Pure substances possess :
variable melting points and boiling points
nonuniform composition
variable properties
fixed melting points and boiling points
The heterogeneous mixture of soot particles in air is a mixture of :
solid-in-solid
solid-in-gas
gas-in-solid
gas-in-gas
Identify the compound from the following.
Iron
