Pure substances possess :
variable melting points and boiling points
nonuniform composition
variable properties
fixed melting points and boiling points
We separate mixtures to :
remove unwanted components
to get pure substances
both the above
none of the above
Pick out the liquid-in-gas type of mixture from the following.
Dissolved carbon dioxide in water
Droplets of water in air
Oxygen dissolved in water
All of the above
A coagulant is :
special chemical which helps small fine particles to settle down
which helps the substance to sublime
filtering agent
Sieving can be used only when the components of the mixture have :
different sizes
different melting points
different boiling points
different specific gravities
Mixtures in which components can be distingushed are called :
heterogeneous
homogenous
pure substances
solutions
The process by which a solid changes directly into gas is called :
decantation
sublimation
condensation
sedimentation
A small boy mischievously mixed small pebbles into a bag of pulses. What method will you employ to separate the mixture ?
Magnetic separation
Crystallisation
Handpicking
Filtration
Identify the compound from the following.
Carbon dioxide
Iron
Hydrogen
Air
Decantation is a :
process of transferring the clear liquid without disturbing the sediments
process of separating an insoluble solid from a liquid using filter paper
process of settling down heavier , insoluble particles from a mixture
process by which a solid changes directly into the vapour state
