Exercise – I
Q1. Fill in the blanks.
(a) __________ is present in both living and non-living things.
(b) The tendency of an element to exist in two or more forms but in the same physical state is called __________.
(c) __________ and __________ are the two major crystalline allotropes of carbon.
(d) __________ is the hardest substance that occurs naturally.
(e) The name ‘carbon’ is derived from the Latin word __________.
Answer:
(a) Carbon is present in both living and non-living things.
(b) The tendency of an element to exist in two or more forms but in the same physical state is called Allotropy.
(c) Crystalline and non- crystalline are the two major crystalline allotropes of carbon.
(d) Diamond is the hardest substance that occurs naturally.
(e) The name ‘carbon’ is derived from the Latin word carbo.
Q2. Choose the correct alternative.
(a) In combined state, carbon occurs as
(i) coal
(ii) diamond
(iii) graphite
(iv) petroleum
Answer: D
(b) A crystalline form of carbon is
(i) lampblack
(ii) gas carbon
(iii) sugar
(iv) fullerene
Answer: C
Q4. Define the following terms:
(a) Allotropy
(b) Carat
(c) Crystal
(d) Catenation
Answer:
(a) Allotropy: The phenomenon that causes an element to exist is known as allotropy. With same chemical properties but differing physical qualities, in two or more forms in the same physical state.
(b) Carat – A diamond’s weight is measured in carats (1 carat = 0.2 g).
(c) Crystal – A crystal is a homogeneous material made up of atoms, molecules, or ions that are arranged in a certain pattern. As a result, a crystal has a distinct geometrical shape and planar surfaces, such as sugar and sodium chloride.
(d) Catenation – The ability of the carbon atom to join with other carbon atoms to build lengthy chains by sharing electrons is the reason why there are so many organic compounds. Catenation is a characteristic of carbon that makes it special.
Q5. State the terms:
(a) Substances whose atoms or molecules are arranged in a definite pattern.
(b) Different forms of an element found in the same physical state.
(c) The property by which atoms of an element link together to form long chain or ring compounds.
Answer:
(a) Substances whose atoms or molecules are arranged in a definite pattern. – Crystals.
(b) Different forms of an element found in the same physical state. – Allotropy.
(c) The property by which atoms of an element link together to form long chain or ring compounds. – Catenation
Q6. Name the following:
(a) The hardest naturally occurring substance.
(b) A greyish black non- metal that is a good conductor of electricity.
(c) The third crystalline form of carbon.
Answer:
(a) The hardest naturally occurring substance is Diamond.
(b) A greyish black non- metal that is a good conductor of electricity is Graphite.
(c) The third crystalline form of carbon is Fullerenes.
Q7. Answer the following Questions:
(a) Why is graphite a good conductor of electricity but not diamond?
(b) Why is diamond very hard?
(c) What are fullerenes? Name the most common fullerenes.
(d) What impurity is present in black diamond?
(e) Explain the softness of graphite with reference to its structure.
Answer:
(a) Graphite is a good conductor of electricity because each carbon atom in a graphite molecule has one free valence electron. They don’t have any free mobile electrons in diamond, however. Diamonds are therefore poor electrical conductors.
(b) A diamond is essentially a huge molecule. Four valence electrons make up one atom of carbon. As a result, each carbon atom is connected to four of its neighbors. Creating a solid tetrahedral structure as a result. Diamond is the hardest material due to its strong bonding.
(c) Fullerenes: The third crystalline form of carbon is called a fullerene. Despite the fact that they were just recently found. They have been discovered to exist in both the earth’s geological formations and interstellar dust. Typical fullerenes include C-32, C-50, and C-70 and C-76
(d) Black diamonds have copper oxide present in them as impurity.
(e) In a graphite molecule of each carbon atoms is linked with three neighboring carbon atoms. Thus forming a hexagonal arrangement of atoms. These hexagonal grouping of carbon atoms are arranged as layers or sheets piled on the top of other. The layers are held together by weak forces such that they can slide over one another. That is why graphite is soft.
Q8. Give two uses of (a) graphite (b) diamond.
Answer:
(a) Uses of graphite:
1. For making the electrodes of electric furnaces.
2. For making crucibles for melting metals due to its high melting points.
(b) Uses of Diamond:
1. Diamond is used in jewelers as a gem
2. It is used for cutting and drilling rocks, glass,
Q9. Write three differences between graphite and diamond.
Answer:
Exercise – II
Q1. Fill in the blanks:
(a) __________ is formed when charcoal is burnt in a limited supply of air.
(b) Coal is a __________ form of carbon.
(c) __________ is the most inferior form of coal.
(d) Wood charcoal is a __________ conductor of heat and electricity.
(e) __________ is used in making black shoe polish.
Answer:
(a) Carbon monoxide is formed when charcoal is burnt in a limited supply of air.
(b) Coal is an amorphous form of carbon.
(c) Peat is the most inferior form of coal.
(d) Wood charcoal is a bad conductor of heat and electricity.
(e) lampblack is used in making black shoe polish.
Q2. Choose the correct alternative
(i) Anthracite is
(a) an inferior type of coal
(b) a superior type of coal
(c) a cheapest form of coal
(d) none of above
Answer: B
(ii) Destructive distillation of coal yields
(a) coal tar
(b) coal gas
(c) coke
(d) all of the above
Answer: D
(iii) Lamp black is
(a) an amorphous form of carbon
(b) a crystalline form of carbon
(c) a pure form of carbon
(d) a cluster of carbon atoms
Answer: A
(iv) The process by which decayed plants slowly convert into coal is called.
(a) Petrification
(b) Carbonization
(c) Carbonification
(d) Fermentation
Answer: B
(v) The purest form of the amorphous carbon is
(a) wood charcoal
(b) sugar charcoal
(c) bone charcoal
(d) lampblack
Answer: B
Q3. Write ‘true’ or ‘false’ against the following statements:
(a) Charcoal is a good adsorbent.
(b) Coke is obtained by destructive distillation of sugar.
(c) Activated charcoal is a good conductor of electricity.
(d) Wood charcoal is an important constituent of gun powder.
(e) Coal gas is used in the preparation of artificial fertilizers.
Answer:
(a) Charcoal is a good adsorbent. True
(b) Coke is obtained by destructive distillation of sugar. False
(c) Activated charcoal is a good conductor of electricity. False
(d) Wood charcoal is an important constituent of gun powder. True
(e) Coal gas is used in the preparation of artificial fertilizers. False
Q4. Define the following:
(a) Carbonization
(b) Adsorption
(c) Bone black
Answer:
(a) Carbonization: Carbonization is the term for the gradual transformation of plant matter into carbon-rich materials.
(b) Adsorption: The ability of a substance to absorb gases, liquids, and solids on its surface is known as adsorption.
(c) Bone black: By treating bone charcoal with hydrochloride acid, which dissolves the calcium phosphate, the carbon portion of the charcoal is separated. The solution is subsequently filtered to remove the carbon, and this is how bone black is created.
Q5. Name the following:
(a) Substances whose atoms or molecules are not arranged in a geometrical pattern. – Amorphous
(b) The best variety of coal. – Bituminous
(c) The purest form of amorphous carbon. – Anthracite
(d) An amorphous form of carbon that contains about 98% carbon. – Anthracite
(e) Mixture of carbon monoxide and hydrogen. – Water gas.
Q6. Answer the following Qs:
(a) What is destructive distillation? What are the products formed due to the destructive distillation of coal?
(b) Why is wood charcoal used in water filters and gas masks?
(c) How is wood charcoal made locally? What other substances are formed in the process.
(d) How many carbon atoms are there in Buckminster fullerenes?
Answer:
(a) Destructive Distillation: When a substances is heated in the absence of air. The process is called destructive distillation. Products formed are: Coke, Coal tar, Coal gas and ammonia solution.
(b) Due to its high adsorbing capacity, wood charcoal is used as gas masks to adsorb harmful gases. Wood charcoal is porous, that is why it is used to filter water.
(c) Wood charcoal is prepared when wood is heated in a limited supply of air. Locally wood charcoal is prepared by piling logs of wood one above the other with a gap in the centre of the pile. The pile is covered with wet clay to prevent the entry of air. A few holes are left at the bottom of the pile. The wood is set on fire. After some time when fire dies out, wood charcoal is left behind. The other substances are -wood tar, pyroligneouscid and wood gas.
(d) 60 carbon atoms are arranged in spherical structure in Buck minster fullerenes.
Q7. (a) Describe the formation of coal.
(b) Name four types of coal with percentage of carbon present in each, with uses.
Answer:
(a) Coal formation: Coal was created over millions of years. The bacterial breakdown of ancient plant debris that had been hurriedly buried beneath a series of layers of dirt gave rise to coal. Vegetable matter that had decomposed into coal under conditions of high pressure and temperature and the absence of air.
(b) Coal Types:
1. Peat: It has a light brown colour and only 50 to 60 percent carbon. It is the lowest quality of coal.
2. Lignite: It has a carbon content of greater than 60%. It is tougher than peat and has a brown colour.
3. Bituminous: It contains 90%, 80%, and 70–75% carbon. The most popular type of coal and the type utilized for household use is bituminous coal.
4. Anthracite, the finest metal variety of coal. Its carbon contents vary between 92 – 98%. It is hard, dense and black, difficult to ignite.
Uses of coal:
1. Coal is used as both domestic and industrial fuel.
2. It is used to prepare coke, coal gas and coal tar.
Q8. Name the products formed when:
(a) Wood is burnt in the absence of air.
(b) Bone is heated in the absence of air.
(c) Diamond is burnt in air at 900°C.
(d) Graphite is subjected to high pressure and 3000°C temperature.
Answer:
(a) Wood charcoal is created while burning wood with little to no air.
(b) Bone charcoal, bone oil, and the organic chemical pyridine.
(c) Carbon dioxide
(d) Artificial diamond.
Q9. Give two uses for each of the following:
(a) Coal
(b) Coke
(c) Wood charcoal
(d) Sugar charcoal
(e) Bone charcoal
(f) Lampblack
Answer:
(a) Coal
(i) It serves as a fuel for both home and commercial purposes.
(ii) It is used to make coal tar, coal gas, and coke.
(b) Coke
(i) In smelting furnaces, coke is utilized as a smokeless fuel.
(ii) It is employed in the production of producing gas and water.
(c) Wood charcoal
(i) Wood charcoal is used as a fuel.
(ii) It plays a significant role in gun powder.
(d) Sugar Charcoal
(i) The main function of sugar charcoal is as a reducing agent.
(ii) Colored solutions are discolored with it.
(e) Bone Charcoal
(i) It is extensively used to decolorize cane-sugar in the process of manufacturing sugar.
(ii) It is also used in the manufacture of large number of phosphorous compounds.
(f) Lamp Black
(i) It is used in making black shoe polish.
(ii) It is used in the manufacture of tiers and gun powder.
Q10. Give balanced equations for the following chemical reactions:
(a) wood charcoal and cone, nitric acid
(b) coke and steam
(c) wood charcoal and lead monoxide.
Answer:
(a) Wood charcoal and cone, nitric acid
C + 4HNO3 + CO2 → 4NO2 + 2H2O
(wood charcoal)
(b) Coke and steam
C + H2O → CO + H2
Coke Steam (water gas)
(c) wood charcoal and lead monoxide
Exercise – III
Q1. (a) Name the chemicals required for the preparation of carbon dioxide in the laboratory.
(b) How will you collect the gas?
(c) Write the balanced chemical equation for the above reaction.
(d) Draw a labelled diagram for the preparation of CO2 in the laboratory.
(e) Why is sulphuric acid not used for the preparation of carbon dioxide in the laboratory?
Answer:
(a) Hydrochloric acid in diluted form with calcium carbonate.
(b) By air being forced upward.
(c) CaCO3 + 2HCl result CaCl2, H2O, and CO2.
(d) Carbon dioxide preparation in a laboratory
(e) Calcium carbonate interacts with diluted sulfuric acid. However, it is not utilized since the calcium sulphate produced during the process is water insoluble. The reaction is halted and the marble chips are covered.
CaCO3 + H2SO4 (dil.) → CaSO4 + H2O + CO2
(calcium (Sulphuric (calcium (water) (Carbon
carbonate) acid) sulphate) dioxide)
Q2. Write the balanced chemical equations for the preparation of carbon dioxide by:
(a) Heating calcium carbonate.
(b) The action of acetic acid on sodium bicarbonate.
(c) The action of dilute sulphur acid on sodium bicarbonate.
Answer:
(a) Heating calcium carbonate
(b) The action of acetic acid on sodium bicarbonate
NaHCO3 + CH3COOH → CH3COONa + H2O + CO2
(c) The action of dilute sulphuric acid on sodium bicarbonate
NaHCO3 + H2SO4 (dil.) → NaHSO4 + H2O + CO2(g)
Q3. What happens when:
(a) A lit splinter is introduced into a jar containing carbon dioxide?
(b) Moist blue litmus paper is placed in a jar containing carbon dioxide?
(c) Carbon dioxide is passed through lime water first in small amounts and then in excess?
(d) A baking mixture containing baking powder is heated?
(e) A soda water bottle is opened?
Answer:
(a) A lit splinter goes out.
(b) Red coloration of blue litmus paper.
(c) Lime water turns milky when CO2 is added in tiny amounts; but, when added in large amounts, the milkiness vanishes.
(d) Carbon dioxide is created.
(e) The bottled gas escapes when the pressure is released with a bristling effervescence that gives the beverage fizz.
Q4. Give reasons for the following:
(a) An excess of carbon dioxide increases the temperature of the earth.
(b) Soda acid and foam types of fire extinguisher are not used for extinguishing electrical fires.
(c) Solid carbon dioxide is used for refrigeration of food.
Answer:
(a) Excess of carbon dioxide increases the temperature of the earth. Due to rise in temperature ice in the Polar Regions may melt causing floods in coastal regions island.
(b) In both of these fire extinguishers, the solutions are prepared in water, which conducts electricity. As a result an electric shock might result, which might lead to short- circuiting and another fire.
(c) Solid carbon dioxide serves as a coolant and refrigeration for preserving food articles.
Q5. What is a fire extinguisher? What is the substance used in the modern type of fire extinguishers? How is it an improvement over the soda acid-type and the foam-type fire extinguishers?
Answer:
Fire extinguishers are tools that create carbon dioxide in a variety of forms to be used as an extinguishing agent. It is a contemporary style of fire extinguisher where pressurized liquid carbon dioxide is kept in a steel cylinder. Foam and soda-acid extinguishers cannot be used to put out fires because they are prepared in water, which conducts electricity and could result in a short circuit that starts another fire.
Q6. Explain the term ‘greenhouse effect’. How can it be both beneficial and harmful for life on earth?
Answer:
The trapping of the earth’s radiated energy by carbon dioxide present in air, so as to keep the earth warm, is called ‘greenhouse effect’. Green house is beneficial because this principle is applied to grow plants in colder regions. Carbon dioxide increases the temperature of atmosphere. Due to rise in temperature; ice in the Polar Regions may melt, causing floods. So it is harmful for life on earth.
Q7. What steps should be taken to balance carbon dioxide in the atmosphere?
Answer:
Since climate change will lead to an ecological system that is out of balance, considerable efforts should be made to balance the amount of carbon dioxide in the atmosphere. Among these actions are:
• Adding more plants and trees.
• Using smokeless energy sources, such as solar power, biogas, etc.
• Installing filters in the chimneys of manufacturing facilities and power plants.
Q8. State three ways by which carbon dioxide gas is added into the atmosphere.
Answer:
1. By planting more trees.
2. By combustion of fuels
3. By decay of dead animals, plants and plants products.
Exercise – IV
Q1. Fill in the blanks:
(a) __________ is formed when carbon is burnt in a limited supply of air or oxygen.
(b) Carbon monoxide bums in air with a pale __________ to form carbon dioxide.
(c) Carbon monoxide is a products of __________ combustion.
(d) A mixture of 95% oxygen and 5% carbon dioxide is called __________.
(e) Carbon dioxide is used as a __________ in the extraction of pure metals from their corresponding ores.
Answer:
(a) Carbon monoxide is formed when carbon is burnt in a limited supply of air or oxygen.
(b) Carbon monoxide bums in air with a pale blue flame to form carbon dioxide.
(c) Carbon monoxide is a product of incomplete combustion.
(d) A mixture of 95% oxygen and 5% carbon dioxide is called carbogen.
(e) Carbon dioxide is used as a reducing agent in the extraction of pure metals from their corresponding ores.
Q2. Match the following.
Answer:
Q3. How is carbon monoxide gas formed?
Answer:
When a significant amount of carbon or its compounds are burned in a small amount of oxygen or air, the main byproduct is carbon monoxide. This prevents the absorption of oxygen. Denying oxygen to the cells in our bodies. As a result, breathing becomes difficult, which results in death.
Q4. State the poisonous nature of carbon monoxide?
Answer:
Gaseous carbon monoxide is extremely toxic. Inhaling air with 0.5% carbon monoxide by volume can be fatal. This is because the hemoglobin found in our body’s blood cells reacts with carbon monoxide to create a stable molecule.
Q5. Give two uses of carbon monoxide.
Answer:
Below are the uses of carbon monoxide:
• Carbon monoxide is a strong reducing agent.
• Carbon monoxide is used in the extraction of pure metals from their ores.
Q6. Why carbon monoxide is called silent killer?
Answer:
Burning coal or wood with little available oxygen results in the production of carbon monoxide. People cannot feel the gas because it is colorless and has a barely perceptible odor, making it a silent killer.
Q7. Explain the reducing action of carbon monoxide.
Answer:
Reducing action of carbon- monoxide: Carbon monoxide is a strong reducing agent. It reduces the oxides of the less active metals to their respective metals and itself gets oxidized to carbon dioxide.
Q8. Write two remedies for carbon monoxide poisoning.
Answer:
1. The victim should immediately bring out into the open.
2. The victim should be given artificial respiration with carbogen.
Q9. Complete the reactions and balance them.
(a) CuO + CO →
(b) Fe2O2 + CO →
Answer:
