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Class 10 Class 12
Give reasons for the following:
All metals have metallic bonds but some metals are soft and having low melting points and some are hard and having high melting points.

The strength of metallic bond depends upon the numbr of valence electrons of the metal atom and the magnitude of forces binding these electrons to the nuclei. Thus the strength of metallic bond in different metals may be weak or strong, hence their nature (soft or hard) and their melting points may be different.
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Why do solids have a definite volume?

A solid have a definite volume because the inter molecular distance  between its molecules are fixed.
1439 Views

Refractive index of a solid is observed to have the same value along all directions. Comment on the nature of this solid. Would it show clevage property?

Refractive index of a solid which have the same value along all directions are isotropic in nature. It would not show cleavage property.
1055 Views

Why is glass considred a super-cooled liquid?

Glass is amorphous solids and  have a tendency to flow, though very slowly. Therefore, these are called pseudo solids or super cooled liquids .
1368 Views

Why are solids rigid?

Solids are rigid because the internuclear distance between the  molecules of a solid are very less and closely packed and their positions are fixed due to the strong forces of attraction between them.
2488 Views

Classify the following as amorphous or crystalline solids: Polyurethane, naphthalene, benzoic acid, teflon, potassium nitrate, cellophane, polyvinyl chloride, fibre glass, copper.

Amorphous solids: Polyurethane, teflon, cellophane, polyvinyal chloride, fibre glass.
Crystalline solids: naphthlene, benzoic acid, potassium nitrate, copper.
1237 Views