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  1. Asked: In:

    Name the technique to separate salt from sea-water.

    Devesh

    Evaporation

    Evaporation

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  2. Asked: In:

    Name the technique to separate butter from curd.

    Devesh

    Butter can be separated from curd by the technique called centrifugation.

    Butter can be separated from curd by the technique called centrifugation.

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  3. Asked: In:

    How will you separate a mixture containing kerosene and petrol (difference in their boiling points is more than 25ºC), which are miscible with each other?

    Devesh

    A mixture of kerosene and petrol which are miscible with each other can be separated by distillation. Method Take a mixture in a distillation flask.  Fit it with a thermometer. Arrange the apparatus as shown in the figure. Heat the mixture slowly. Petrol vaporises first as it has lower boiling pointRead more

    A mixture of kerosene and petrol which are miscible with each other can be separated by distillation.
    Method

    • Take a mixture in a distillation flask.
    •  Fit it with a thermometer.
    • Arrange the apparatus as shown in the figure.
    • Heat the mixture slowly.
    • Petrol vaporises first as it has lower boiling point. It condenses in the condenser and is collected from the condenser outlet.
    •  Kerosene is left behind in the distillation flask.
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  4. Asked: In:

    To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293 K. Find its concentration at this temperature.

    Devesh

    Mass of solute (sodium chloride) = 36 g Mass of solvent (water) = 100 g Mass of solution = Mass of solute + Mass of solvent = 36 g + 100 g = 136 g Concentration (mass by mass percentage) of the solution =𝑀𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 / 𝑀𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡×100 % =36/136×100 % =26.4 %

    Mass of solute (sodium chloride) = 36 g
    Mass of solvent (water) = 100 g
    Mass of solution = Mass of solute + Mass of solvent
    = 36 g + 100 g = 136 g

    Concentration (mass by mass percentage) of the solution
    =𝑀𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 / 𝑀𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡×100 %
    =36/136×100 %
    =26.4 %

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  6. Asked: In:

    How are sol, solution and suspension different from each other?

    Devesh

    Sol They are heterogeneous in nature. They scatter a beam of light and hence show Tyndall effect. They are quite stable. Solution They are homogeneous in nature. They do not scatter a beam of light and hence do not show Tyndall effect. Examples of solution are: salt in water, sugar in water. SuspensRead more

    Sol

    They are heterogeneous in nature. They scatter a beam of light and hence show Tyndall effect. They are quite stable.

    Solution

    They are homogeneous in nature. They do not scatter a beam of light and hence do not show Tyndall effect. Examples of solution are: salt in water, sugar in water.

    Suspension

    They are heterogeneous in nature. They scatter a beam of light and hence show Tyndall effect. Examples of suspension are: sand in water, dusty air.

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