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प्रश्न
How does graphite act as a lubricant?
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उत्तर
Graphite has a hexagonal structure and weak van der Waals force between the layers of the carbon atoms in its crystal. Due to this weak force, the layers of carbon atoms in graphite can slide over one another, making graphite slippery in nature and capable of acting as a lubricant.
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संबंधित प्रश्न
Explain why carbon forms compounds mainly by covalent bond.
State the reason to explain why covalent compounds "have low melting and boiling points."
Name the black substance of pencil. Will the current flow through the electrical circuit when we use the sharpened ends of the pencil to complete the circuit?
Write two points of difference in the structures of diamond and graphite.
Explain why, graphite can be used as a lubricant but diamond cannot.
A saturated hydrocarbon has fifty hydrogen atom in its molecule. The number of carbon atoms in its molecule will be
(a) twenty five
(b) twenty four
(c) twenty six
(d) twenty seven
An element A has 4 valence electrons in its atom whereas element B has only one valence electron in its atom. The compound formed by A and B does not conduct electricity. What is the nature of chemical bond in the compound formed? Give its electron-dot structure.
An element E exists in three allotropic forms A, B and C. In allotrope A, the atoms of element E are joined to form spherical molecules. In allotrope B, each atom of element E is surrounded by three other E atoms to form a sheet like structure. In allotrope C, each atom of element E is surrounded by four other E atoms to form a rigid structure.
(a) Name the element E.
(b) What is allotrope A.
(c) What is allotrope B?
(d) What is allotrope C?
(e) Which allotrope is used in making jewellery?
(f) Which allotrope is used in making anode of a dry cell?
Define a covalent bond.
For each compound mentioned above give the formulae of ions formed in aqueous solution.
Give two example in following case:
Gaseous polar compounds
Explain the following briefly:
Sodium chloride dissolves in water but carbon tetra chloride is insoluble in water.
Explain the following briefly.
Pure water does not conduct electricity, but on adding sodium chloride to it, it starts conducting electricity.
An element L consists of molecules.
What type of bonding is present in the particles that make up L?
Explain the following:
Water is a polar covalent molecule.
Define a covalent bond.
Generally, the melting and boiling point of carbon compounds are found to be less than _______ °C.
The I.U.P.A.C name of CH3CH2CH = CH2 is?
Assertion (A): Melting point and boiling point of ethanol are lower than that of sodium chloride.
Reason (R): The forces of attraction between the molecules of ionic compounds are very strong.
