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प्रश्न
What is meant by a substance?
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उत्तर
A substance is a kind of matter that is made up of only one type of particle (either atoms or molecules). It has a definite composition and distinct properties. A substance may be an element (e.g., oxygen, iron) or a compound (e.g., water, carbon dioxide). For example, water is a pure substance because it contains only one type of molecule, H₂O.
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संबंधित प्रश्न
Differentiate between homogeneous and heterogeneous mixtures with examples.
Three mixtures A, B and C are obtained by stirring three different solids in water taken in separate beakers. When mixture A is allowed to stand for some time, then its particles settle at the bottom of the beaker. When a beam of light is passed through mixture A in a dark room, the path of light becomes visible when observed from the side of the beaker. When mixture B is allowed to stand for a considerable time, even then its particles do not settle down. Mixture B, however, scatters the beam of light just like mixture A. The particles of mixture C do not settle down on keeping and it also does not scatter a beam of light passing through it.
What are the mixtures like A known as ?
What are the mixtures like B known as ?
What are the mixtures like C known as ?
Name the phenomenon exhibited by A and B which occurs on passing a beam of light through them.
Name one mixture each which is like (i) A (ii) B, and (iii) C.
Name the process you would use to separate a mixture of two miscible liquids (like acetone and water).
Name any two solid substances whose mixture can be separated by sublimation.
Name one pair of substances whose mixture can be separated completely by distillation.
Name the following:
The component of the soluble solid-liquid mixture, which is lost to the atmosphere on heating.
Suggest separation technique(s) one would need to employ to separate the following mixture.
Mercury and water
Give an example of each mixture having the following characteristics. Suggest a suitable method to separate the components of this mixture
Two volatile components with appreciable differences in boiling points.
A colloid is a ______ mixture and its components can be separated by the technique known as ______.
A mixture of chloroform and water are taken in a separating funnel is mixed and left undisturbed for some time. The upper layer in the separating funnel will be of ______ and the lower layer will be that of ______.
