Question:
(a) What is a physical change ? Give two examples of physical changes.
(b) What is a chemical change ? Give two examples of chemical changes.
Answer:
(a)Physical changes :-1 No new substancc is formed in a physical change.
2. A physical change is a temporary change.
3. A physical change is easily reversible.
4. Very little heat (or light) energy is usually absorbed or given out in a physical change.
5. The mass of a substance does not alter in a physical change. :-1.A new substance is formed in a chemical change.
2.A chemical change is a permanent change.
3.A chemical change is usually irreversible.
4.A lot of heat (or light) energy is absorbed or given out in a chemical change.
5.The mass of a substance does alter in a chemical 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.
Name one pair of liquids which can be separated by using a separating funnel.
Q 3.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 4.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
Q 5.
Name one pair of substances whose mixture can be separated by fractional distillation.
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.
What are non-aqueous solutions?
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.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 10.
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 11.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 12.
Name a non-metal which is a good conductor of electricity.
Q 13.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 14.
Give two reasons for supposing that water is a compound and not a mixture.
Q 15.
What is the concentration of a solution which contains 16 g of urea in 120 g of solution ?
Q 16.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 17.
Name the process which can be used to separate a mixture of salt solution and sand.
Q 18.
Define Brownian movement in colloids.
Q 19.
State whether the following statement is true or false : Milk is a pure substance.
Q 20.
Name any two solid substances whose mixture can be separated by sublimation.
Q 21.
What are the kinds of mixture?
Q 22.
What is saturated solution? Explain with an example.
Q 23.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 24.
Name the elements are in liquid state at room temperature.
Q 25.
Who used the term 'element' first time?
Q 26.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 27.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 28.
Name the source from which nitrogen and oxygen are obtained on a large scale.
Q 29.
Name one pair of substances whose mixture can be separated completely by distillation.
Q 30.
What are different categories of pure substance?
Q 31.
Name two properties of a substance to check its purity?
Q 33.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 34.
What is an unsaturated solution?
Q 35.
What are different ways to separate solid mixtures?
Q 36.
How many elements are there which are in gaseous state at room temperature?
Q 37.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 38.
Name a metal which is soft and a non-metal which is hard.
Q 39.
What are pure substances ? Give two examples of pure substances.
Q 40.
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 41.
Which of the two will scatter light: soap solution or sugar solution ? Why ?
Q 42.
(a) What is meant by a solution ? Give two examples of solutions.
(b)What is a suspension ? Give two examples of suspensions.
(c)
Q 43.
Name the process you would use to separate a mixture of anthracene and copper sulphate ?
Q 44.
How will you separate a mixture of chalk powder and water ?
Q 45.
Name the process which is used in milk dairies to separate cream from milk.
Q 46.
Name the apparatus you would use to separate oil from water.
Q 47.
How will you separate iron pins from sand ?
Q 48.
On the basis of composition, how matter is classified?
Q 49.
What is meant by solute and solvent?
Q 50.
What factors affect the solubility of solvent and solute?
