Question:
Explain with an example what is a colloid?
Answer:
A colloid is intermediate between suspension and solution. A homogenous-looking heterogeneous mixture in which particles have size between 1 nm to 100nm (1 nano-m = 10-9 m) and are dispersed in a continuous medium is called a colloid. A Colloidal solution is also called a sol. The continuous medium in a sol is called the dispersion medium and the particles form the dispersed phase or colloidal particles. Examples of colloids are: milk, blood, toothpaste, jelly, fog, cloud etc.
Is Matter Around Us Pure?
Q 1.
What is the general name of the process by which tea-leaves are separated from prepared tea ?
Q 2.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
Q 3.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 4.
Name one pair of substances whose mixture can be separated by fractional distillation.
Q 5.
Name one pair of liquids which can be separated by using a separating funnel.
Q 6.
What type of magnet is fitted on a crane to separate scrap iron objects from a heap of waste materials in factories ?
Q 7.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 8.
Define Brownian movement in colloids.
Q 9.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 10.
Give two reasons for supposing that water is a compound and not a mixture.
Q 11.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 12.
What are non-aqueous solutions?
Q 13.
What is saturated solution? Explain with an example.
Q 14.
To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293K. Find its concentration at this temperature.
Q 15.
Name a non-metal which is a good conductor of electricity.
Q 16.
Name the process which can be used to separate a mixture of salt solution and sand.
Q 17.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 18.
State the differences between compounds and mixtures.
Q 19.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 20.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 21.
What is the concentration of a solution which contains 16 g of urea in 120 g of solution ?
Q 22.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 23.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 24.
Name the source from which nitrogen and oxygen are obtained on a large scale.
Q 25.
Name the apparatus you would use to separate oil from water.
Q 26.
What are the kinds of mixture?
Q 27.
What is meant by solute and solvent?
Q 28.
What are different ways to separate solid mixtures?
Q 29.
Who used the term 'element' first time?
Q 30.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 31.
State whether the following statement is true or false : Milk is a pure substance.
Q 32.
What is the general name of the materials which contain at least two pure substances and show the properties of their constituents ?
Q 33.
What are pure substances ? Give two examples of pure substances.
Q 34.
How is cream separated from milk ?
Q 35.
What are different categories of pure substance?
Q 37.
What is a compound? Give an example.
Q 38.
What is an unsaturated solution?
Q 39.
What are the physical states of dispersed phase and dispersion medium of a cloud?
Q 40.
What are the properties of a colloid?
Q 41.
How are sol, solution and suspension different from each other?
Q 42.
A solution contains 40 mL of ethyl alcohol mixed with 100mL of water. What is the concentration of the solution in terms of volume by volume percentage?
Q 43.
Winnowing works on what property?
Q 44.
Name the technique to separate
(i) butter from curd
(ii) salt from sea-water
(iii) camphor from salt
Q 45.
How many elements are there which are in gaseous state at room temperature?
Q 46.
Name the elements are in liquid state at room temperature.
Q 47.
Give examples of liquids that are
(i) completely miscible
(ii) partially miscible
(iii) practically immiscible
Q 48.
What is meant by saying that metals are malleable and ductile ?
Q 49.
(a) What is a physical change ? Give two examples of physical changes.
(b) What is a chemical change ? Give two examples of chemical changes.
Q 50.
Name the process you would use to separate a mixture of anthracene and copper sulphate ?
