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.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 2.
State the differences between compounds and mixtures.
Q 3.
What is a solution? What are the properties of a solution?
Q 4.
What are the characteristics exhibited by a pure substance?
Q 5.
What are the properties of suspensions?
Q 6.
What are the differences and similarities between concentration and solubility?
Q 7.
What are the reasons for separating the constituents of a mixture?
Q 8.
Name two properties of a substance to check its purity?
Q 9.
What factors affect the solubility of solvent and solute?
Q 10.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 11.
What are suspensions? Explain with an example.
Q 12.
What is meant by a pure substance?
Q 13.
How crystallization is better than evaporation?
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.
What are the advantages of preparing solutions?
Q 16.
Why air is a mixture not a compound? Give reasons.
Q 17.
Name the elements are in liquid state at room temperature.
Q 19.
Based on the type of solvent, how solutions are classified?
Q 20.
Based on the amount of solute in the given solution, how solutions are classified?
Q 21.
What are the properties of a colloid?
Q 22.
How many elements are there which are in gaseous state at room temperature?
Q 23.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 24.
A good method to separate alum (phitkari) from impure samples is
(a) Filtration
(b) Sedimentaion
(c) Crystallization
(d) Sublimation
Q 25.
How will you separate iron pins from sand ?
Q 26.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 27.
What are the physical states of dispersed phase and dispersion medium of a cloud?
Q 28.
State three reasons why you think air is a mixture and water is a compound.
Q 29.
Name the process you would use to separate a mixture of two miscible liquids (like acetone and water).
Q 30.
Name the technique to separate
(i) butter from curd
(ii) salt from sea-water
(iii) camphor from salt
Q 31.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 32.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 33.
What is difference between colloids and suspensions ?
Q 34.
21.5 g of sodium chloride dissolves in 60 g of water at 25°C. Calculate the solut water at that temperature.
Q 35.
What is meant by Solubility?
Q 36.
What are the various methods to express concentration of a solution?
Q 37.
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 38.
Is air a mixture or a compound ? Give three reasons for your answer.
Q 39.
What is the most common way of expressing the concentration of a solution ?
Q 40.
Name the process by which the various gases of the air are separated.
Q 41.
(a) Name the process by which all the dye can be recovered from black ink.
(b) Name the process by which the various dyes' (coloured materials) present in black ink can be separated.
Q 42.
What are different categories of pure substance?
Q 43.
What are the characteristics of mixture?
Q 44.
What are aqueous solutions?
Q 45.
What are non-aqueous solutions?
Q 46.
When we open the cap of a cola drink (or any carbonated beverage), why does excess of bubbles come out?
Q 47.
What are different ways to separate solid mixtures?
Q 48.
What is Chromatography?
Q 49.
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 50.
Who used the term 'element' first time?
