Question:
What are the properties of a colloid?
Answer:
Properties of a colloid are:
- Heterogeneous nature: Colloid or Sol is heterogeneous in nature i.e. it can be seen only with a powerful microscope.
- Particle Size: Colloid particle size lies between 1nm (10-9 m) to 100 nm (10-7 m)
- Separation of colloidal particles by filtration: Colloidal particles cannot be separated from the mixture by the process of filtration. But, a special technique of separation known as centrifugation.
- Brownian Motion: When seen under microscope, the colloidal particles in a colloid are seen to be moving in a random fashion, called Brownian motion.
- Stability: They do not settle down when left undisturbed, that is, a colloid is quite stable.
- Tyndall effect: Colloid exhibit Tyndall effect. When a light is passed through sol kept in dark room, the path of light beam is visible. It is due to scattering of light by colloidal particles and this effect is called Tyndall effect.
- Electrophoresis: Man colloidal particles may have electrical charge (+ve or -ve) on them. When an electric current passes through a sol, colloid particles move towards opposite charged electrodes. This process is called electrophoresis.
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.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 3.
Name one pair of liquids which can be separated by using a separating funnel.
Q 4.
What are non-aqueous solutions?
Q 5.
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 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.
Name one pair of substances whose mixture can be separated by fractional distillation.
Q 8.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 9.
State whether the following statement is true or false : Milk is a pure substance.
Q 10.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 11.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 12.
What are the reasons for separating the constituents of a mixture?
Q 13.
How many elements are there which are in gaseous state at room temperature?
Q 14.
Who used the term 'element' first time?
Q 15.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 16.
Fill in the following blanks with suitable words :
(a) An element is made up of only one kind of...........atoms
(b)Brine is a..........whereas alcohol is a.......
(c) Brass is an alloy which is considered a..........
(d) The three important metalloids are.............and...........
(e) The elements which are sonorous are called...............
Q 17.
Is air a mixture or a compound ? Give three reasons for your answer.
Q 18.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 19.
Name one pair of substances whose mixture can be separated completely by distillation.
Q 20.
Name the apparatus you would use to separate oil from water.
Q 22.
What is an unsaturated solution?
Q 23.
What is saturated solution? Explain with an example.
Q 24.
Explain with an example what is a colloid?
Q 25.
What do you mean by strength of the solution?
Q 26.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 27.
Name the following :
(a) a lustrous liquid metal.
(b) a liquid non-metal
(c) a metal which can be cut with a knife
(d) a non-metal which is good conductor of electricity.
(e) an element which melts when kept on the palm.
(f) the best conductor of heat.
Q 28.
Name the elements are in liquid state at room temperature.
Q 29.
What are the differences and similarities between concentration and solubility?
Q 30.
Name a metal which is soft and a non-metal which is hard.
Q 31.
Name a non-metal which is a good conductor of electricity.
Q 32.
Classify the following into elements and compounds :
(i)
Q 33.
State three reasons why you think air is a mixture and water is a compound.
Q 34.
Define a compound. Give two points of evidence to show that sodium chloride is a compound.
Q 35.
Name a non-metal :
(a) which is lustrous
(b) which is required for combustion
(c) whose one of the allotrophic forms is a good conductor of electricity. Name the allotrope.
(d) other than carbon which shows allotropy
(e) which is known to form the largest number of compounds
Q 36.
Name a metal :
(a) which can be easily cut with a knife
(b) which forms amalgams
©which has not fixed shape
(d) which has a low melting point
(e) which is yellow in colour
Q 37.
Which of the two will scatter light: soap solution or sugar solution ? Why ?
Q 38.
What is the most common way of expressing the concentration of a solution ?
Q 39.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
Q 40.
Define
(a) solute, and
(b) solvent
Q 41.
What is difference between colloids and suspensions ?
Q 42.
What is meant by the concentration of a solution ?
Q 43.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 44.
What is a solution? What are the properties of a solution?
Q 45.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 46.
What are the properties of a colloid?
Q 47.
Give examples of liquids that are
(i) completely miscible
(ii) partially miscible
(iii) practically immiscible
Q 48.
What name is given to those elements which are neither good conductors of electricity like copper nor insulators like sulphur ?
Q 49.
A 15% alcohol solution means :
(a)15 mL alcohol and 85 mL water.
(b)15 mL alcohol and 100 mL water.
Choose the correct answer.
Q 50.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
