Question:
Name two properties of a substance to check its purity?
Answer:
A pure substance has a fixed melting point or boiling point at constant pressure. The purity of a substance can be tested by checking its melting point or boiling point. If a substance is impure i.e. it contains traces of another substance, the melting and boiling point of that substance will change.
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.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 4.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 5.
What is meant by solute and solvent?
Q 6.
Name one pair of substances whose mixture can be separated by fractional distillation.
Q 7.
Name one pair of liquids which can be separated by using a separating funnel.
Q 8.
What is a solution? What are the properties of a solution?
Q 9.
What are non-aqueous solutions?
Q 10.
What is saturated solution? Explain with an example.
Q 11.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 12.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 13.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 14.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
Q 15.
Name the source from which nitrogen and oxygen are obtained on a large scale.
Q 16.
Name the apparatus you would use to separate oil from water.
Q 17.
What is an unsaturated solution?
Q 18.
What are the various methods to express concentration of a solution?
Q 19.
Name the technique to separate
(i) butter from curd
(ii) salt from sea-water
(iii) camphor from salt
Q 20.
What are the differences and similarities between concentration and solubility?
Q 21.
Define Brownian movement in colloids.
Q 22.
State whether the following statement is true or false : Milk is a pure substance.
Q 23.
Name a metal which is soft and a non-metal which is hard.
Q 24.
Name a non-metal which is a good conductor of electricity.
Q 25.
What is meant by saying that metals are malleable and ductile ?
Q 26.
What are pure substances ? Give two examples of pure substances.
Q 27.
Give two reasons for supposing that water is a compound and not a mixture.
Q 28.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 29.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 30.
Name one pair of substances whose mixture can be separated completely by distillation.
Q 31.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 32.
What is Chromatography?
Q 33.
Name the elements are in liquid state at room temperature.
Q 34.
Why solutions do not exhibit Tyndall effect?
Q 35.
Name the process which can be used to separate a mixture of salt solution and sand.
Q 36.
What are different categories of pure substance?
Q 37.
What are the kinds of mixture?
Q 38.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 39.
Why do fish go in deep waters during day light?
Q 40.
What are the properties of suspensions?
Q 41.
How crystallization is better than evaporation?
Q 42.
Who gave the first explanatory definition of 'element'?
Q 43.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 44.
Which of the following will show Tyndall effect ? Why ?
(a) Salt solution
(b) Starch solution
(c)Milk
Q 45.
What type of magnet is fitted on a crane to separate scrap iron objects from a heap of waste materials in factories ?
Q 46.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 47.
On the basis of composition, how matter is classified?
Q 48.
What factors affect the solubility of solvent and solute?
Q 49.
What are aqueous solutions?
Q 50.
What are the advantages of preparing solutions?
