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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
Write the number of covalent bonds in the molecule of butane, C4H10.
Butanone is a four-carbon compound with the functional group:
Give one example of a molecule containing a single covalent bond.
will CCl4 conduct electricity or not?
give reason for your choice.
State one use of diamond which depends on its 'extraordinary brilliance' and one use of graphite which depends on its being 'black and quite soft'.
What is graphite?
The atomic numbers of four elements P, Q, R and S are 6, 10, 12 and 17 respectively. Which two elements can combine to form a covalent compound?
(a) P and R
(b) Q and S
(c) P and S
(d) R and S
The electronic configurations of three elements X, Y and Z are as follows:
| X | 2, 4 |
| Y | 2, 7 |
| Z | 2, 1 |
(a) Which two elements will combine to form an ionic compound?
(b) Which two elements will react to form a covalent compound?
Give reasons for your choice.
What do you understand by polar covalent compounds?
Draw an electron dot structure of the following molecule. (Without showing the circle) :
Methane
Give reason as to why hydrogen chloride can be termed as a polar covalent compound.
Draw an electron dot diagram to show the formation of the following compound.
Magnesium chloride [ H=1, C=6, Mg=12, Cl=17].
Element A has 2 electrons in its M shell. Element B has atomic number 7.
If B is a diatomic gas, write the equation for the direct combination of A and B to form a compound.
Name gas with a rotten egg smell.
Number of valence electrons in a carbon atom is _______.
Write the molecular formula of the given compound.
Acetic acid
Complete the following activity.
Write the names of the hydrocarbons for the following structural formula.
(isobutylene, cyclohexane, propene, cyclohexene, cyclopentane, benzene, propyne, isobutane, propane)
 |
Which of the following are correct structural isomers of butane?
- \[\begin{array}{cc}
\ce{H}\phantom{...}\ce{H}\phantom{...}\ce{H}\phantom{...}\ce{H}\\
|\phantom{....}|\phantom{....}|\phantom{....}|\\
\ce{H - C - C - C - C - H}\\
|\phantom{....}|\phantom{....}|\phantom{....}|\\
\ce{H}\phantom{...}\ce{H}\phantom{...}\ce{H}\phantom{...}\ce{H}\\
\end{array}\] - \[\begin{array}{cc}
\ce{H}\phantom{...}\ce{H}\phantom{...}\ce{H}\\
|\phantom{....}|\phantom{....}|\\
\ce{H - C - C - C - H}\\
|\phantom{.....}|\phantom{.....}|\\
\ce{H}\ce{H-C-H}\ce{H}\\
|\\
\ce{H}\\
\end{array}\] - \[\begin{array}{cc}
\ce{H}\phantom{...}\ce{H}\phantom{...}\ce{H}\\
|\phantom{....}|\phantom{....}|\\
\ce{H - C - C - C - H}\\
|\phantom{.....}\backslash\phantom{..}|\\
\phantom{....}\ce{H}\phantom{......}\ce{C - H}\phantom{}\\
\phantom{.......}|\\
\phantom{.......}\ce{H}\\
\end{array}\] - \[\begin{array}{cc}
\ce{H}\phantom{...}\ce{H}\\
|\phantom{....}|\\
\ce{H - C - C - H}\\
|\phantom{....}|\\
\ce{H - C - C - H}\\
|\phantom{....}|\\
\ce{H}\phantom{...}\ce{H}\\
\end{array}\]
Mineral acids are stronger acids than carboxylic acids because
- mineral acids are completely ionised
- carboxylic acids are completely ionised
- mineral acids are partially ionised
- carboxylic acids are partially ionised
______ is an example of a covalent compound having a high melting point.
