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प्रश्न
There are three substances X, Y and Z. The substance X does not have a fixed melting point or boiling point and it still shows the individual properties of its constituents. The substance Y is a pure substance which occurs in nature as such. The substance Y has a fixed melting point and boiling point but it cannot be broken down into simpler substances by any chemical means. The substance Z is also a pure substance whose properties are entirely different from those of its constituents. The substance Z can, however, be divided by electrolysis into two substances which belong to the same class of substances as Y.
- What type of substance could X be ? Name one substance like X.
- What type of substance could Y be ? Name one substance like Y.
- What type of substance could Z be ? Name one substance like Z.
- Which process involves absorption or release of an appreciable amount of energy : formation of substance X or formation of substance Z ?
- Name the three groups into which all the substances like Y are divided on the basis of their properties.
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उत्तर
- Substance X does not have a fixed melting or boiling point. Moreover, it shows the properties of its constituents. So, it must be a mixture. Sugar solution in water is a substance like X.
- Substance Y has a fixed melting or boiling point but it cannot be split into simpler substances by chemical processes. Hence, it must be an element. Hydrogen is a substance like Y.
- Substance Z is also a pure substance whose properties are entirely different from those of its constituents. Hence, it must be a compound. Sugar is a substance like Z.
- Formation of Z (a compound) involves absorption or release of an appreciable amount of energy.
- The three groups are metals, non-metals and metalloids. All the substances like Y are divided into these groups on the basis of their properties.
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संबंधित प्रश्न
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- gases
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All kinds of matter
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Name the property which enables metals to be drawn into wires.
What are pure substances ? Give two examples of pure substances.
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Name a metal which has a low melting point.
Which of the following is not an element ?
State whether the following statement is true or false :
Sponge is an example of solid sol.
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 source from which nitrogen and oxygen are obtained on a large scale.
How will you separate water from mustard oil ?
Draw a labelled diagram of the fractional distillation apparatus used for separating a mixture of alcohol and water.
Differentiate between the-two characteristics of matter – ‘mass’ & ‘weight’.
If there is a sudden shower, we take shelter under a roof at the roadside. Even though the rain does not fall on us directly, we get wet to some extent. Why ?
Intermolecular space is maximum in ______.
The phenomenon of Evaporation takes place at the ______ of a liquid.
Evaporation is always accompanied by ______ in temperature.
