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Kerala State Syllabus 9th Standard Chemistry Solutions Chapter 7 The World of Carbon
The World of Carbon Textual Questions and Answers
Activities In The Text
Find the position of carbon in the periodic table and the complete the table.
|Electron configuration No. of electrons in the||2, 4|
What are allotropes?
Different forms of the same element having different physical properties but with same chemical properties are known as Allotropes and this phenomenon is called Allotropy.
What are the characteristics of diamond.
- Very hard
- Not a conductor of electricity
- High thermal conductivity
- High refractive index
Write the uses of diamond
- It is used to make ornaments.
- It is used for cutting glass.
Explain the structure of diamond with Figure?
In diamond each carbon atom is linked by covalent bond with four other carbon atom surrounding it. This strong bonding is responsible for the hardness of diamond. Due to the absence of free electron in this crystal structure, it does not conduct electricity
Write the important properties of Graphite?
- It is Gray in color
- It is good conductor of electricity
- It is a smooth solid
- It does not vapourize
- It is Lustrous
- It is nonvolatile
Give reason Graphite is used as a lubricant to reduce friction in machine parts?
It is a smooth solid. It does not vapourize. It also has high melting point
Explain the structure of Graphite?
In Graphite each carbon atoms is united with three surrounding carbon atom through covalent bond and forms a sheet-like structure. These sheets or layers are stacked one above the other to form three dimensional structure.
Each layer is made up of hexagons there is no covalent bonding between the layers. These layers are held together by weak Vander Waal’s physical forces. Hence these layers can slide over one another.
What are amorphous carbon?
Cock, coal, charcoal, bone charcoal, etc. are non-crystalline allotropes of carbon. These are commonly called amorphous carbon.
Which carbon compound is present in the atmosphere?
Which carbon compound is produced by the combustion of fuels?
How carbon dioxide is prepared of in the laboratory?
Carbon dioxide is prepared in the laboratory by the action of marble piece or calcium carbonate with dil.
HCl CaCO3 + 2HCl → CaCl2 + H2O + CO2
Which are the reactants are used to prepare carbon dioxide (CO2) in the laboratory?
CaCO3 and HCl
Complete the equation of the reaction
CaCO3 + 2HCl → CaCl2 + H2O + CO2
How can we identify that the gas formed here is C02?
- Show a burning splinter into the gas. It gets extinguished.
- lt turns lime water in milky
Which properties of CO2 are familiar to you?
What are the properties of carbon dioxide known to you? Tick the correct ones given below.
- Coloured / Colourless✓
- Supports combustion / Does not support combustion✓
- Denser than air / Density higher than air✓
- Has a characteristic odor/ Odourless ✓
Whether the aqueous solution of CO2 is acidic or alkaline?
Acidic (carbonic acid, H2CO3)
Write the chemical formulae and uses of some carbonates.
Na2CO3 – Soda ash
CaCO2 – limestone, marble.
How carbonates can be identified.
Add some dilute HC; to the given salt. If a colorless gas that turns lime-water milky is formed, that salt will be a carbonate. The gas formed is CO2.
The variety of carbon compounds is essential for the existence of life on the earth. Figure shows the ways in which carbon dioxide is exchanged over the earth. This is known as carbon cycle.
Name the process by which carbon dioxide is utilized by plants?
What are the activities that increase the amount of carbon dioxide in air?
Combustion, Respiration, Decomposition
Is the tremendous increase in the amount of CO2 in atmosphere advantages?
No, It causes greenhouse effect. Greenhouse effect is the reason for global warming.
What is green house effect?
The process of increasing atmospheric temperature due to the increase in the amount of carbon dioxide in the atmosphere is called green house effect.
What is global warming?
As a result of the green house effect, the average temperature of the earth and atmosphere increases. This is known as global warming.
Discuss the consequences of global warming in the following.
1. In ice layers
2. In ocean islands
3. In the field of agriculture
4. In the climate
- Ice layers melt and rivers will be flooded
- The ocean islands will be submerged.
- Fields of agriculture will be submerged
- Causes rise in atmospheric temperature.
Suggest some measures to resist global warming effectively.
- Limit the use of fossil fuels
- Plant more trees
Give the uses of carbon dioxide?
- It is used in fire extinguisher
- It is used for the preparation of soda water/soft drink
- It is used for the preparation of washing soda, baking soda, etc.
- It is used for the preparation of fertilizers like urea
- Used for the preparation of carbogen which is used for artificial breathing. Carbogen is 95% 02 and 5% C02
- Dry ice is solid carbon dioxide, which is used in stage shows for creating special effects resembling clouds.
How carbon monoxide is formed?
Carbon dioxide is the gas formed when carbon reacts with oxygen.
However, if the relative amount of carbon increases or that of oxygen decreases the reaction takes place as given below.
2C + O2 → 2CO
- The gas thus formed is carbon monoxide. It is a poisonous gas.
- It is formed by the incomplete combustion of carbon in a limited supply of air.
How carbon monoxide becomes fatal?
When carbon monoxide is inhaled, it reacts with the hemoglobin in the blood and forms carboxy hemoglobin. As a result, the oxygen-carrying capacity of blood decreases leading even to death.
What measures can be taken to avoid situations that produce carbon monoxide?
- Avoid incomplete combustion
- Ensure the supply of oxygen.
- Service motor vehicles regularly
Explain the use of carbon monoxide?
- Used as a gaseous fuel
- Industrially important gases like water gas (A mixture of CO and H2) producer gas (A mixture of CO and N2)
- Used as reducing agent in metallurgy
Write the chemical formulae of washing soda baking soda and marble.
Washing Soda (Na2CO3.10H2O)
Baking soda (NaHCO3)
What is organic compounds?
Organic compounds are carbon compounds except the inorganic compounds like CO,CO2, carbonates, bicarbonates etc.
How many electrons are there in the outermost shell of carbon?
What is the valency of carbon?
Complete the table given below.
What are hydrocarbon?
Hydrocarbons are compounds containing only car¬bon and hydrogen.
What is catenation?
Catenation is the ability of the atoms of an element to combine among themselves. In comparison to other elements, the ability for catenation is very high for carbon.
What are characteristics responsible for the increase in number of carbon compounds?
- Valency of carbon is 4
- Ability of catenation is high
- Single, double and triple bonds are possible be-tween carbon atoms.
- Carbon atoms combine together to form many straight-chain, ring or branched-chain compounds.
The names of some allotropes of carbon, their properties and uses are given in the table, but not in the correct order Match them suitably.
- Manufacture of ornaments
- High refractive index
- Electric conductor
Some statements related to carbon monoxide and carbon dioxide are given. Classify them correctly.
a) formed as a result of the incomplete combustion of carbon compounds’
b) aqueous solution shows acidic nature.
c) poisonous gas
d) used in fire extinguishers
e) an be used as a fuel
f) formed as a result of the complete combustion of carbon compounds.
g) can be prepared from carbonates and bicarbonates.
h) is a component of producer gas and water gas.
a) carbon monoxide
b) Carbon dioxide
c) Carbon monoxide
d) Carbon dioxide
e) Carbon monoxide
f) Carbon dioxide
g) Carbon dioxide
h) Carbon monoxide
a) Write the chemical formula of calcium carbonate.
b) Which gas is formed when calcium carbonate reacts with acids?
c) What is the name of an aqueous solution of this gas?
b) Carbon dioxide
c) Soda water (carbonic acid)
Graphite, which is an allotrope of carbon, is a con-ductor of electricity. But diamond, another allotrope is not a conductor of electricity. Why?
diamond each carbon atom is linked by covalent bond with four other carbon atom surrounding it. This strong bonding is responsible for the hardness of diamonds. Due to the absence of free electron in this crystal structure, it does not conduct electricity
Write the structure of a straight-chain and a a ring hydrocarbon having four carbon atoms.
Arrange the objects as shown in the figure and conduct the experiment. Based on your observations, what is the conclusion that you reach at?
The bulb glows because pencil led or graphite is a good conductor of Electricity.
Lighted candles of different lengths are arranged in a trough as shown in the figure. Pour a saturated solution of sodium bicarbonate (baking soda) into the trough. Add a little vinegar to the solution. What do you observe? Give reasons for the observation.
Candle with smallest height is extinguished first and the candle with highest height is extinguished last. The reason is the density of carbon dioxide is greater than that of air. Carbon dioxide is produced when baking soda react with vinegar.
Let’s make a fire extinguisher Arrange the apparatus as shown in the figure (a). Add the vinegar contained in a test tube to the sodium bicarbonate (baking soda) solution (figure b) by tilting the wash bottle. Introduce the resultant gas to a candle flame. Record your observation. What is your inference?
The candle flame gets extinguished. The reason is when Baking soda reacts with vinegar to produce carbon dioxide.