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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.
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
Define matter. Give four examples of matter.
Classify the following as elements or compounds :
Iron, Iron sulphide, Sulphur, Chalk, Washing soda, Sodium, Carbon, Urea
Which of the following are compounds ?
- CO
- No
- NO
- Co
Iron powder and sulphur powder were mixed together and divided into two parts A and B. When part A was heated strongly over a burner, then a substance C was formed. The part B was, however, not heated at all. When dilute hydrochloric acid was added to substance C, then gas D was evolved and when dilute hydrochloric acid was added to part B then gas E was evolved.
- What type of substance is B ?
- What type of substance is C ?
- Name the gas (i) D, and (ii) E ?
- State one characteristic property of gas D.
- Write one test to identify gas E.
Define solvent.
How will you differentiate between a suspension and a colloid ?
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.
State whether the following statement are true or false :
Alcohol can be separated from a mixture of alcohol and water by a separating funnel.
Name the process by which common salt is purified.
How will you separate iron pins from sand ?
Pure copper sulphate can be obtained from an impure sample by the process of :
The material which is added to water during purification process at the water works so as to disinfect it is :
The given mixture contains three constituents A, B and C. The constituent A is a yellow coloured, solid element which dissolves in a liquid D. The constituent B is a blue coloured salt which is insoluble in liquid D but dissolves easily in another liquid E. The constitudent C is a liquid which is used in cooking food and forms a solid fat on hydrogenation.
(a) What do you think could (i) constituent A, and (ii) liquid D be ?
(b) What could (i) constituent B, and (ii) liquid E be ?
(c) What could liquid C be ?
(d) How will you separate the mixture containing A, B and C ?
What type of matter glass is?
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 |
Non-metals are usually poor conductors of heat and electricity. They are non-lustrous, non-sonorous, non-malleable and are coloured.
Name a non-metal which exists as a liquid at room temperature.
Atoms or groups of atoms having a charge are called ______.
Solid is an arrangement of particles ______.
Define the term matter.
Write a scientific reason.
Lemon sherbat has sweet, sour and salty taste and it can be poured in a glass.
