Give two examples each for Aerosol, (ii) Emulsion.
(i) Aerosol: Clouds, smoke (ii) Emulsion: Milk, face cream.
Identify colloids and true solutions from the following: Pond water, fog, aluminium paint, vinegar and glucose solution.
True solutions are vinegar and glucose solution. Colloids are fog, aluminium paint.
Explain why particles of a colloidal solution do not settle down when left undisturbed, while in the case of a suspension they do.
Particle size in a suspension is larger than those in a colloidal solution. Also molecular interaction in a suspension is not strong enough to keep the particles suspended and hence…
Why is it not possible to distinguish particles of a solute from the solvent in solution?
A true solution is homogeneous in nature. The solute and solvent particles are very small. They cannot be distinguished even under a microscope.
Sea water can be classified as homogeneous as well as heterogeneous mixture.” Comment.
Sea water is a mixture of salts and water which cannot be separated except by evaporation. Therefore, sea water is considered homogeneous. Sea water also contains mud, decayed plant, etc.,…
Identify the elements from the following substances: sulphur, brine, hydrochloric acid, water, neon, paper, sugar.
The elements are sulphur and neon.
An unknown substance A’ on thermal decomposition produces ‘B’ and C’. What is ‘A’-an element, a compound or a mixture?
Unknown substance A' should be a compound because elements and mixture do not decompose.
Name two elements which exist in liquid state at room temperature.
Gallium and mercury exist in liquid state at room temperature.
Which of the following are physical changes? Melting of iron metal, rusting of iron, bending of iron rod, drawing a wire of iron metal.
Melting of iron metal, bending of iron rod and drawing a wire of iron metal are physical changes because there is no change in the chemical composition of iron, only…
Why is water called universal solvent?
Water is known as universal solvent because it has the ability to dissolve wide variety of substance.