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प्रश्न
What is meant by saying that metals are lustrous ?
उत्तर
Metals are said to be lustrous because of their property to shine.
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संबंधित प्रश्न
Name the processes involved in two cases.
Name the terms for the change of vapour into a liquid.
Which type of elements, metals or non-metals, show the property of brittleness ?
Classify the following as elements or compounds :
Iron, Iron sulphide, Sulphur, Chalk, Washing soda, Sodium, Carbon, Urea
State two physical properties on the basis of which metals can be distinguished from non-metals.
Name a metal which has a low melting point.
Classify the following into elements, compounds and mixtures :
arble, Air, Gold, Brass, Sand, Diamond, Graphite, Petroleum, Common salt, Sea-water, Chalk
Which of the following are compounds ?
- CO
- No
- NO
- Co
The element which is not common between the compounds called baking soda and soda ash is
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.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
Define the Emulsion Give one example.
What is a colloid ? Give two examples of colloids (or colloidal solutions)
Differentiate between a saturated and an unsaturated solution. How will you test whether a given solution is saturated or not ?
How is scrap iron separated from a heap of waste materials in factories?
The liquid air has three components X, Y and Z whose boiling points are : –186°C, –183°C and –196°C,
respectively. When liquid air is fed into a tall fractional distillation column from near its bottom and warmed
up slowly :
(a) Which component will be collected from near the bottom of the fraction distillation column ? Why ?
(b) Which component will be collected from the top part of the fractional distillation column ? Why ?
(c) Which component will be collected from the middle part of the fractional distillation column ? Why ?
(d) What could the component X, Y and Z be ?
Justify your answer.
| Figure 1 | Figure 2 | Figure 3 |
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The arrangement of particles in three different phases of matter is shown above.
- Which state is represented by Fig. 1?
- In which state will the inter-particle attraction be maximum?
- Which one of them cannot be contained in an open vessel?
- Which one can take the shape of its container?
Match the physical quantities given in column A to their S I units given in column B:
| (A) | (B) | ||
| (a) | Pressure | (i) | cubic metre |
| (b) | Temperature | (ii) | kilogram |
| (c) | Density | (iii) | pascal |
| (d) | Mass | (iv) | kelvin |
| (e) | Volume | (v) | kilogram per cubic metre |
Gases change to liquid by the process of ______.
The fluidity of solids: ______.
