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प्रश्न
Explain why, graphite can be used as a lubricant but diamond cannot.
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उत्तर
Because of its softness and non-volatile nature, graphite is used as a lubricant in the fast moving parts of a machinery. It is used for lubricating the parts of machinery which operate at high temperatures. Diamond, on the other hand, is an extremely hard substance; therefore, it cannot be used as a lubricant.
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संबंधित प्रश्न
Name the type of bonds formed in ionic compounds and in the compounds formed by carbon.
What do you call the compounds having the same molecular formula but different structural arrangements of atoms?
Fill in the following blank with suitable word:
The form of carbon which is known as black lead is ...........
What type of bonds are present in CO2 molecule? Draw their electron-dot structures.
Explain why covalent compounds have generally high melting points?
One of the following compounds is not ionic in nature. This compound is:
(a) Lithium chloride
(b) Ammonium chloride
(c) Calcium chloride
(d) Carbon tetrachloride
A hydrocarbon having one double bond has 100 carbon atoms in its molecule. The number of hydrogen atoms in its molecule will be
(a) 200
(b) 198
(c) 202
(d) 196
A solid element X has four electrons in the outermost shell of its atom. An allotrope Y of this element is used as a dry lubricant in machinery and also in making pencil leads.
(a) What is element X?
(b) Name the allotrope Y.
(c) State whether allotrope Y is a good conductor or non-conductor of electricity.
(d) Name one use of allotrope Y (other than lubrication and pencil leads)
(e) Name two other allotropes of element X.
State the type of bonding in the following molecule.
Methane
Complete the following:
When the nuclei of two different reacting atoms are of ______ mass, then a bond so formed is called ______ covalent bond. (equal, unequal, polar, non-polar)
Give examples for the following:
Two liquid non polar compounds.
Explain the following:
Covalent compounds have low melting and boiling point.
(a) Compound X consists of molecules.
Choose the letter corresponding to the correct answer from the choices (a), (b), (c) and (d) given below
X is likely to have a :
Acids dissolve in water to produce positively charged ions. Draw the structure of these positive ions.
What do you understand by dipole (polar) molecule?
Element A has 2 electrons in its M shell. Element B has atomic number 7.
If the compound formed between A and B is melted and an electric current is passed through the molten compound, the element A will be obtained at the ______ and B at the ______ of the electrolytic cell.
Give an example of the covalent bond formed by
(i) Similar atoms (ii) Dissimilar atoms
Write scientific reason.
Benzene compounds are called aromatic compounds.
Complete the following activity.
Write the names of the hydrocarbons for the following structural formula.
(isobutylene, cyclohexane, propene, cyclohexene, cyclopentane, benzene, propyne, isobutane, propane)
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