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प्रश्न
What is chromatography ? State its two applications.
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उत्तर
Chromatography is a technique used for separating two or more dissolved solids, which are present in the solution in small quantities.
Separation is based on the fact that two or more substances are soluble in the solvent but their solubility is different.
This technique has various important applications:
- To separate dyes present in black ink
- It is used in forensic science to detect and identify the trace amounts of poison present in the stomach.
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संबंधित प्रश्न
Match the following
| Column A | Column B | ||
| (a) | Molecules | (i) | Water boils |
| (b) | 100° C | (ii) | Evaporation |
| (c) | 0° C | (iii) | Changes from solid to gas |
| (d) | At all temperatures | (iv) | Matter |
| (e) | Camphor | (v) | Water freezes |
Define matter.
Give one difference between atoms and molecules.
Which one is a kind of matter:
All kinds of matter
Name a metal which is soft and a non-metal which is hard.
Name a non-metal :
- which is lustrous
- which is required for combustion
- whose one of the allotrophic forms is a good conductor of electricity. Name the allotrope.
- other than carbon which shows allotropy
- which is known to form the largest number of compounds
Which of the following statements are true for pure substances ?
- pure substances contain only one kind of particles
- pure substances may be compounds or mixtures
- pure substances have the same composition throughout
- pure substances can be exemplified by all elements other than nickel
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.
Which of the following are chemical changes and which physical ? Give reason.
- a glass bottle breaking
- coal burning in air
- making a cake
- wool being knitted into a sweater
One of the following does not show Tyndall effect. This one is :
Name the process by which the various gases of the air are separated.
How will you separate a mixture of iron filings, chalk powder and common salt ?
Which of the following mixture cannot be separated by using water as the solvent ?
______ is a smallest particle.
Which of the following are homogeneous in nature?
(i) ice
(ii) wood
(iii) soil
(iv) air
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.
Solids do not flow.
Evaporation does form bubbles.
Gas-solid is ______.
