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प्रश्न
A, B and C are all liquids. Liquid A has a comparatively low boiling point. On heating, liquid A vaporises completely without leaving behind any residue. Liquid A is being used increasingly as a fuel in motor vehicles either alone or by mixing with petrol. Liquid B has a very high boiling point. It also vaporises completely on heating, without leaving any residue. Liquid B is a conductor of electricity and used in making thermometers. Liquid C has a moderate boiling point. On heating, liquid C vaporises leaving behind a white solid D which is used in cooking vegetables. The condensation of vapours from C give a liquid E which turns anhydrous CuSO4 to blue.
(a) Which liquid could be an element ? Name this element.
(b) Which liquid could be a mixture ? Name this mixture.
(c) Which liquid could be a compound ? Name this compound.
(d) What could the solid D be ?
(e) What do you think is liquid E ?
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उत्तर
- Liquid B has a very high boiling point. It also vaporises on heating. It is a conductor of electricity and is used in making thermometers. So, B could be an element. Further, liquid B is mercury as mercury is a liquid metal, which expands on heating and is used extensively in thermometers.
- Liquid C has a moderate boiling point. It could be a mixture. It is a salt solution because when C is heated, it vaporises and leaves behind a white solid (salt), which is used in the process of cooking.
- Liquid A is used in motor vehicles as fuel, either alone or after mixing with petrol. It could be a compound because on heating, it does not leave any residue. It is alcohol as alcohol is being used in motor vehicles nowadays.
- Solid D is sodium chloride. It is also known as common salt and is added in food.
- Liquid E is water as, on heating, liquid C, which is a salt solution, leaves water vapours. On condensing these vapours, we obtain pure water. When water is mixed with anhydrous copper sulphate, we obtain a blue colour solution. This is because of the formation of hydrated copper sulphate solution.
\[\ce{CuSO4 + 5H2O →\underset{\text{hydrated copper sulphate}}{CuSO4.5H2O}}\]
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संबंधित प्रश्न
Match the following
| Column A | Column B | ||
| (a) | Molecules | (i) | Water boils |
| (b) | 100° C | (ii) | Evaporation |
| (c) | 0° C | (iii) | Changes from solid to gas |
| (d) | At all temperatures | (iv) | Matter |
| (e) | Camphor | (v) | Water freezes |
What do you mean by the inter-molecular spaces? How do they vary in different states of matter?
Define the following term of Matter .
What are the three groups into which all the elements can be divided ? Name two elements belonging to each group.
Which of the following are not compounds ?
Chlorine gas, Potassium chloride, Iron powder, Iron sulphide, Aluminium foil, Iodine vapour, Graphite, Carbon monoxide, Sulphur powder, Diamond
What is meant by (i) elements (ii) compounds, and (iii) mixtures ?Write down the names of two elements, two compounds and two mixtures.
Which of the following does not have a fixed melting point/boiling point ?
What happens when the temperature of a saturated sugar solution is increased ?
Fill in the following blank :
Milk is a .................... solution but vinegar is a .................... solution.
You have been given a suspension and a solution. How could you tell the difference between them by their appearance ?
What will happen if a saturated solution is :
- heated
- cooled
What is a colloid ? Give two examples of colloids (or colloidal solutions)
When the solid A is added to water, it dissolves with the evolution of a lot of heat and making little explosions to form two products B and C. The properties of products B and C are entirely different from those of solid A as well as water. Moreover, products B and C cannot be reconverted into solid A and water. When another solid D is added to water, it dissolves with the absorption of a little heat to form a product E which cools down. The product E shows the properties of both, solid D as well as water. Moreover, product E can be converted into solid D and water.
(a) What type of change occurs when solid A is dissolved in water ? Why ?
(b) What type of change occurs when solid D is dissolved in water ? Why ?
(c) Name a metal which you think could behave like solid A. Also name the products B and C.
(d) Name the solid D if it is the one which is used in making ordinary dry cells.
(e) Name the process by which D can be recovered from E.
What is fractional distillation ? What is the use of fractionating column in fractional distillation ?
Name one pair of liquids which can be separated by using a separating funnel.
Solids possess very high kinetic energy.
Solids do not flow.
______ is used for industrial refrigeration and transporting frozen food.
Give an example of a molecule.
Define the term matter.
