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प्रश्न
The pencil leads are made of mainly:
(a) lithium
(b) charcoal
(c) lead
(d) graphite
उत्तर
graphite
The pencil leads are mainly made of graphite.
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संबंधित प्रश्न
Elements forming ionic compounds attain noble gas configuration by either gaining or losing electrons from their outermost shells. Give reason to explain why carbon cannot attain noble gas configuration in this manner to form its compounds.
Using electron-dot diagrams which show only the outermost shell electrons, show how a molecule of nitrogen, N2, is formed from two nitrogen atoms. What name is given to this type of bonding? (Atomic number of nitrogen is 7)
Using electron-dot diagrams which show only the outermost shell electrons, show how a molecule of oxygen, O2, is formed from two oxygen atoms. What name is given to this type of bonding? (At. No. of oxygen = 8)
Draw the electron-dot structure of NH3 and state the type of bonding.
The number of covalent bonds in pentane (molecular formula C5H12) is:
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.
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?
Draw all possible structural formulae of compound from their molecular formula given below.
C3H8
Write answer as directed.
Saturated hydrocarbons are classified into three types. Write these names giving one example each.
Give examples for the following:
Two liquid non polar compounds.
Choose the correct answer from the options given below
Which one is not example of polar covalent compound?
Acids dissolve in water and produce positively charged ions. Draw the structure of these positive ions.
Draw the electron dot diagram and structure of nitrogen molecule.
Potassium (Atomic No. 19) and chlorine (Atomic No. 17) react to form a compound. On the basis of electronic concept, explain
(i) oxidation
(ii) reduction
(iii)oxidising agent
(iv)reducing agent
Number of valence electrons in a carbon atom is _______.
Explain covalent bond with example.
Complete the following activity.
Write the names of the hydrocarbons for the following structural formula.
(isobutylene, cyclohexane, propene, cyclohexene, cyclopentane, benzene, propyne, isobutane, propane)
| \[\begin{array}{cc} \phantom{..}\ce{H}\phantom{...}\ce{H}\phantom{...}\ce{H}\\ \phantom{..}|\phantom{....}|\phantom{....}|\\ \ce{H - C - C- C- H}\\ \phantom{.}|\phantom{....}|\phantom{....}|\\ \ce{H - C - H}\\ |\\\ce{H}\end{array}\] |
The correct structural formula of butanoic acid is
The bond which is formed by the mutual sharing of electrons is called ______ bond.
State the reasons, why carbon cannot
- Lose four electrons to form C4+ cation and
- Gain four electrons to form C4- anion.
How does carbon overcome this problem to form compounds?
