Question:
Why do fish go in deep waters during day light?
Answer:
During day time, the shallow water is warmer and hence it has less dissolved oxygen. Therefore fish tend to go in deep water during day time.
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.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 9.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 10.
Give two reasons for supposing that water is a compound and not a mixture.
Q 11.
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 12.
State whether the following statement is true or false : Milk is a pure substance.
Q 13.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 14.
What is the concentration of a solution which contains 16 g of urea in 120 g of solution ?
Q 15.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 16.
What are the kinds of mixture?
Q 17.
What is saturated solution? Explain with an example.
Q 18.
Define Brownian movement in colloids.
Q 19.
Who used the term 'element' first time?
Q 20.
Name a non-metal which is a good conductor of electricity.
Q 21.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 22.
Name any two solid substances whose mixture can be separated by sublimation.
Q 23.
Name the process which can be used to separate a mixture of salt solution and sand.
Q 24.
What are the characteristics of mixture?
Q 25.
Name the elements are in liquid state at room temperature.
Q 26.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 27.
Which of the two will scatter light: soap solution or sugar solution ? Why ?
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.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 32.
What are different ways to separate solid mixtures?
Q 33.
How many elements are there which are in gaseous state at room temperature?
Q 34.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 35.
Name a metal which is soft and a non-metal which is hard.
Q 36.
What are pure substances ? Give two examples of pure substances.
Q 37.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 38.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 39.
How is cream separated from milk ?
Q 40.
Name two properties of a substance to check its purity?
Q 42.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 43.
What is meant by solute and solvent?
Q 44.
What are the advantages of preparing solutions?
Q 45.
What is an unsaturated solution?
Q 46.
What are suspensions? Explain with an example.
Q 47.
How are sol, solution and suspension different from each other?
Q 48.
What are the reasons for separating the constituents of a mixture?
Q 49.
What is an emulsion? Give examples
Q 50.
Give examples of liquids that are
(i) completely miscible
(ii) partially miscible
(iii) practically immiscible
