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प्रश्न
What name is given to those elements which are neither good conductors of electricity like copper nor insulators like sulphur ?
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उत्तर
Elements that are neither good nor bad conductors of electricity, are called semi conductors.
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संबंधित प्रश्न
Solids have definite shape and definite volume.
What are the two conditions for the interconversion of states of matter ?
Out of solids, liquids and gases, which one has :
- maximum movement of particles ?
- maximum interparticle attractions ?
- minimum spaces between particles ?
What is meant by saying that metals are malleable and ductile?
Which of the following substances are elements ?
Water, Salt, Mercury, Iron, Marble, Diamond, Wood, Nitrogen, Air, Graphite, Hydrogen, Oxygen, Sugar, Chlorine
Which one of the following is not a metalloid ?
What is the most common way of expressing the concentration of a solution ?
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
A solution contains 5.6 mL of alcohol mixed with 75 mL of water. Calculate the concentration of this solution.
You have been given a suspension and a solution. How could you tell the difference between them by their appearance ?
What is meant by the concentration of a solution ?
Milk of Magnesia is :
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.
Name the process you would use to separate a mixture of water and alcohol.
Fill in the following blanks with suitable words :
Immiscible liquids are separated by using a .....................
Describe a method to separate a mixture of camphor and sand.
With the help of a labelled diagram, describe the method of separating ammonium chloride from a mixture of ammonium chloride and common salt. Mention the difference in the properties of ammonium chloride and sodium chloride which has made this separation possible.
Which of the following cannot be separated from air by the process of fractional distillation ?
The non S I and S I units of some physical quantities are given in column A and column B respectively. Match the units belonging to the same physical quantity:
| (A) | (B) | ||
| (a) | degree celsius | (i) | kilogram |
| (b) | centimetre | (ii) | pascal |
| (c) | gram per centimetre cube | (iii) | metre |
| (d) | bar | (iv) | kelvin |
| (e) | milligram | (v) | kilogram per metre cube |
The phenomenon of Evaporation takes place at the ______ of a liquid.
