Ans: Carbon is a non-metallic element which is present on the earth’s crust in free as well as in combined state.
2. What is meant by carbon?
Ans: A naturally abundant, non metallic element that occurs in all organic compounds and can be found in all known forms of life.
3. What are inorganic compounds?
Ans: The compounds which are obtained from minerals or inorganic sources are called inorganic compounds.
4. What are organic compounds?
Ans: The compounds which contain carbon and hydrogen combined together with other elements are called organic compounds.
5. What is organic chemistry?
Ans: The branch of chemistry in which we study about organic compounds is called organic chemistry.
Or
A branch of chemistry that is concerned with carbon and especially carbon compounds which are found in living things.
6. What is water gas?
Ans: Water gas is a mixture of carbon monoxide and hydrogen produced by passing steam over hot carbon.
7. What are allotropes?
Ans: Different forms of an element which exists in different physical forms with slightly different chemical properties are called allotropes.
8. Why is carbon a reactive non-metal?
Ans: Carbon is a reactive non-metal because it combines with many other elements.
9. What is diamond?
Ans: Diamond is one of the hardest allotrope of carbon which is transparent, brilliant and more precious.
10. What is graphite?
Ans: Graphite is soft slippery, black and greasy allotrope of carbon.
11. What is coal?
Ans: Coal is an amorphous allotrope of carbon which is formed in nature as a result of the slow decomposition of organic matter under influence of heat and pressure and limited supply of air
12. How is wood charcoal made?
Ans: Wood charcoal is made by the destructive distillation of wood.
13. How is animal charcoal made?
Ans: Animal charcoal is made by the destructive distillation of degreased bones in iron retorts.
14. What is allotropy?
Ans: The property of an element to exist in different physical forms with slightly different chemical properties is called allotropy.
15. What is co-valency?
Ans: The number of electron pairs which an atom shares to acquire a stable condition is called co-valency.
16. What is a caramel?
Ans: The brown substance with good smell formed on heating sugar is called caramel.
17. What is an inorganic chemistry?
Ans: The branch of chemistry which deals with the study of inorganic compounds is called inorganic chemistry.
18. What is catenation?
Ans: The property of carbon due to which its atom forms a long chain by combining with one another is called catenation.
19. Write any three sources of carbon?
Ans: Some of the main sources of carbon are as follows:
• In air, carbon dioxide is found.
• Various petroleum products.
• In all living organisms, in substances like carbohydrate, starch, urea etc.
20. How does carbon exist in nature?
Ans: Carbon occurs in two forms in nature. They are as follows:
• Free State: Carbon exists as free state in the forms of Graphite, Diamond.
• Combined state: Carbon combines with other elements to form compounds such as carbon dioxide, glucose etc.
21. Write any two properties of carbon.
Ans:
• Carbon has several allotropes or different forms in which it can exist.
• Carbon has ability to make four bonds and is present in many compounds.
22. Write any three chemical properties of carbon with balanced chemical equations.
Ans:
- When carbon is heated with oxygen, and then carbon dioxide gas is formed.
- When carbon is heated with less oxygen, then carbon monoxide is formed.
- When carbon is heated with lead oxide, then carbon dioxide is given out.
23. What is catenation? Write in brief with an example.
Ans: The property of carbon due to which its atoms form a long chain by combining with one another is called catenation.
Carbon is the most common element that exhibits catenation. It can form long hydrocarbon chains and rings like benzene.
24. What is water gas?
Ans: A fuel gas consisting mainly of carbon monoxide and hydrogen, made by passing steam over incandescent coke.
25. What happens when:
Carbon is heated in water vapour?
Ans: When carbon is heated with water vapor, then carbon monoxide and hydrogen gas are formed.C + H2O → CO + H2
26. Apart from the organic beings, where else do we find carbon? Mention the form in which it is available there and also its percentage.
Ans: Carbon is found in atmosphere and earth’s crust. Carbon is found as CO2 in atmosphere and as minerals in earth’s crust. The percentage of carbon in air is 0.03℅ and in earth’s crust about 0.02℅.
27. What is allotropy? Write all the allotropes of carbon.
Ans: Allotropy is phenomena of forming elements having same chemical properties but differing in physical properties. Allotropes of carbon:
• Diamond
• Graphite
• Fullerene
28. Write any four amorphous forms of carbon.
Ans: Amorphous forms of carbon are as follows:
• Charcoal
• Coal
• Coke
• Lampblack
29. What are the properties of diamond?
Ans: The properties of diamond are as follows:
• Colourless transparent substance with extraordinary brilliance due to its high refractive index.
• It's quite heavy.
• It's extremely hard. (Hardest substance known)
• It's doesn't conduct electricity. (Due to absence of free ions)
• It has high thermal conductivity and high melting point.
• It burns on strong getting to form carbon dioxide.
30. Enlist the uses of diamond.
Ans: The uses of diamond are listed below:
• It is used as a precious gem in jewelers.
• It used for cutting glass and marble, black diamond (carbonate) and for boring or drilling on rocks.
• It is used to make a high quality thermometer.
• It is used to make radiation proof windows for spacecraft.
31. What is another name of graphite?
Ans: Plumbago or black lead is another name of graphite.
32. Write the uses of graphite.
Ans: The uses of graphite are as follows:
• The major use of graphite is in making lead pencils of different hardness,
• The presence of free electrons makes graphite a good conductor of electricity and it is used to make electrodes.
• It is used as lubricants.
33. What are the properties of graphite?
Ans: The properties of graphite are as follows:
• It's a greyish black, opaque substance.
• It's lighter than diamond, feels soft and slippery to touch.
• It's good conductor of electricity (due to presence of free ions) but bad conductor of heat.
• On strong heating, it burns to give carbon dioxide.
• It’s insoluble in water and organic solvents
34. What is the reason behind the soft and slippery nature of graphite?
Ans: The different layers of carbon atoms in graphite are held together by weak Vander Waals force of attraction and these layers can slide over each other and makes graphite soft and slippery.
35. Write the uses of fullerene.
Ans: The uses of fullerene are as follows:
• Fullerenes may be used for drug delivery systems in the body and as lubricants.
• It takes part in catalytic processes.
• Used as a therapeutic and diagnostic agent.
• Acts as a potential inhibitor to HIV.
36. Why is fullerene so called?
Ans: Fullerene resembles the framework of dome shaped halls designed by American architect Buckminster fuller so called as fullerenes.
37. What are the properties of fullerenes?
Ans: Properties of fullerenes:
• Fullerenes are stable, but not totally nonreactive.
• Fullerenes are soluble in many solvents like CO2.
• Fullerenes are the only known allotrope of carbon that can be dissolved in common solvents at room temperature like C28, C36 etc.
38. What is the formula of buckyball?
Ans: The formula of buckyball is C60.
39. What is Mho?
Ans: Mho is a unit which is used to measure hardness of the substances.
40. What is soot?
Ans: Lampblack/ black substance formed after burning carbon compounds.
41. State vital force theory?
Ans: According to vital force theory, formation of organic compounds takes place only under the influence of some which is present in the living organism only.
42. What is sugar charcoal?
Ans: Sugar charcoal is a black coloured substance which is formed by heating sugar caramel continuously.
43. Write the differences between:
Diamond and Graphite
Ans: | Diamond | Graphite |
| It is the hardest substance known. | It is soft and slippery. |
| It is transparent and colourless substance with bright appearance. | It is an opaque, dark grey and shiny. |
| It is a bad conductor of heat and electricity. | It is a good conductor of heat and electricity. |
| Its specific gravity is 3.5. | Its specific gravity is 2.2. |
44. Write the differences between:
Organic compounds and Inorganic compounds
Ans: The differences between organic compound and inorganic compound are as follows:| Organic compounds | Inorganic compounds |
| They are insoluble in water. | They are soluble in water. |
| They have low melting and boiling point. | They have high melting and boiling point. |
| They have covalent bonds and cannot be electrolyzed. | They are formed by electrovalent bonds and can undergo electrolysis. |
| They are soluble in organic solvents. | They are insoluble in organic solvents. |
45. Write the differences between:
Ionic compounds and covalent compounds
Ans: The differences between ionic compounds and covalent compounds are as follows:| Ionic compounds | Covalent compounds |
| They are formed by transfer of electrons. | They are formed by sharing of electrons. |
| They generally exist in solid form. e.g. NaCl. | They may be solid (I2), liquid(Br2) or gas(Cl2). |
| Conducts electricity in molten state. | They do not contain ions so they are bad conductor of electricity. |
| They have high melting points and boiling points. | They have low melting points and boiling points. |
44. Define:
Caramel
Ans: Caramel is brunt sugar used for colouring and adding flavor to food.45. Give reasons:
Carbon forms covalent bonds.
Ans: Carbon forms covalent bonds to gain stability, it should lose its valence electrons, gain four more electrons or share its 4 valence electrons with other atoms.46. Give reasons:
Diamond is a bad conductor while graphite is a good conductor of electricity.
Ans: It is because in graphite, carbon forms covalent bonds with only three carbon atoms and there is one free electron in each carbon atom but diamond does not have free electrons.47. Give reasons:
Graphite is used as lubricant.
Ans: Graphite is used as lubricant because it is soft and non-volatile.48. Give reasons:
Diamond is the hardest substance known.
Ans: Diamond is the hardest substance known because each carbon atom in diamond is joined to four other carbon atoms giving rise to a three dimensional rigid and a stable structure.49. Give reasons:
Carbon is a reducing agent.
Ans: Carbon is a reducing agent because it separates metals from their concerning metallic oxide when it is heated with the metallic oxides.C + CuO → Cu + CO
C + PbO → Pb + CO
52. Give reasons:
Organic compounds are non- electrolyte.
Ans: Organic compounds are non electrolyte because they are covalent compounds and they do not dissociate into ions in their molten state and aqueous form.53. Give reasons:
Compounds like Na2CO3, CaCO3, etc. are not organic compounds even though they have carbon.
Ans: It is because they are electrovalent compounds and only covalent compounds having carbon are considered as organic compounds.[CO2 and CO are covalent and have carbon but traditionally they are considered as inorganic ].54. Give reasons:
Molecular formula of calcium carbide is CaC2not Ca2C.
Ans: It is because calcium losses two electrons to form the molecule as it is a metal. The electrons are received by two carbon atoms and they also share three electrons between them.55. What happens when:
Lead oxide is strongly heated with carbon?
Ans: Carbon dioxide is formed separating metal.2PbO + C → 2Pb + CO2
56. Define:
Organic compounds
Ans: The compounds which contain carbon and hydrogen combined together with other elements are called organic compounds.57. Define:
Tetravalency
Ans: Tetravalencey is the state of an atom with four valence electrons available for covalent chemical bonding in its outermost electron shell.58. Define:
Inorganic compounds
Ans: The substances derived from minerals are called inorganic compounds.