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प्रश्न
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.
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उत्तर
- When solid A is dissolved in water, chemical change takes place. This is because the properties of products B and C are entirely different from those of solid A and water.
- Physical change occurs when solid D is dissolved in water. This is because product E shows the properties of both, solid D and water.
- Sodium metal could behave like solid A.
Product B is sodium hydroxide.
Product C is hydrogen. - Solid D is ammonium chloride.
- D can be recovered from E by evaporation.
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संबंधित प्रश्न
Define matter.
Name the terms for the change of a solid into liquid.
Which of the following materials fall in the category of a “pure substance”?
- Ice
- Milk
- Iron
- Hydrochloric Acid
- Calcium oxide
- Mercury
- Brick
- Wood
- Air
When extremely small particles X derived from the anther of a flower were suspended in a liquid Y and observed through a microscope, it was found that the particles X were moving throughout the liquid Y in a very zig-zag way. It was also observed that warmer the liquid Y, faster the particles X moved on its surface.
- What could particles X be ?
- What do you think liquid Y is ?
- What is the zig-zag movement of X known as ?
- What is causing the zig-zag movement of particles X ?
- Name the scientist who discovered this phenomenon.
- What does this experiment tell us about the nature of liquid Y?
Name a non-metal which is a good conductor of electricity.
Name a non-metal which is a good conductor of electricity.
Fill in the following blanks with suitable words :
An element is made up of only one kind of ........
Name two solid, two liquid and two gaseous elements at the room temperature.
Name a metal which has a low melting point.
Which of the following are compounds ?
- CO
- No
- NO
- Co
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 ?
State whether colloidal solutions are homogeneous or heterogeneous.
Pure copper sulphate can be obtained from an impure sample by the process of :
Diffentiate between absorption and adsorption.
______ is a smallest particle.
Which of the following statements are true for pure substances?
(i) Pure substances contain only one kind of particles
(ii) Pure substances may be compounds or mixtures
(iii) Pure substances have the same composition throughout
(iv) Pure substances can be exemplified by all elements other than nickel
Evaporation does form bubbles.
Compressibility of solids: ______.
Give an example of a molecule.
Define the term matter.
