GSEB Solutions for Class 10 Science and Technology – Mineral Coal and Mineral Oil (English Medium)
GSEB SolutionsMathsScience
Question 1:
Select the proper choice from the given multiple choices :
Question 1.1:
Which is the primary state in transformation of coal ?
Solution :
D. Peat
Peat is the primary state of transformation of coal from wood. It contains about 28% of carbon.
Question 1.2:
What is the matured form of coal ?
Solution :
C. Anthracite
Anthracite is a matured form of mineral coal. It contains about 94-98% of carbon.
Question 1.3:
Which type of coal does not produce smoke or odour when burnt ?
Solution :
A. Anthracite
Anthracite contains a small proportion of volatile matter and moisture. When burnt, it does not produce any smoke or smell and the amount of residue is also less.
Question 1.4:
Which of the following components is not obtained when destructive distillation of mineral coal is carried out ?
Solution :
B. Methane
Coke, coal gas, coal tar and ammonia are obtained from the distillation of mineral coal.
Question 1.5:
Which of the following is used in production of water gas ?
Solution :
A. Coke
When water vapour is passed through hot coke, water gas is produced.
C(s) + H2O → (CO + H2)(g)
Question 1.6:
Water gas is the mixture of which gases ?
Solution :
C. Carbon monoxide and hydrogen
Water gas is a mixture of carbon monoxide and hydrogen produced when water vapour is passed through hot coke.
Question 1.7:
Which gas is filled at high pressure in cylinders of household cooking gas ?
Solution :
D. Butane
Cylinders of household cooking gas contain liquefied petroleum gas (LPG) which is mainly butane with small amount of propane plus butane.
Question 1.8:
Which component obtained from refining of petroleum is used as solvent in petrochemicals ?
Solution :
A. Naphtha
Naphtha has C8 to C10 hydrocarbons and is obtained at a range of 393 K to 453 K. It is used as a solvent in petrochemicals.
Question 1.9:
Which of the following is used in petromax to obtain light ?
Solution :
C. Kerosene
The Petromax lamp uses kerosene as fuel to obtain light.
Question 1.10:
Which is the chief hydrocarbon in natural gas ?
Solution :
A. Methane
Methane is the chief component of natural gas.
Other hydrocarbons such as ethane, propane and butane are also present in natural gas.
Question 1.11:
What is the molecular formula of ethene ?
Solution :
C. C2H4
Ethene is an alkene with the general formula CnH2n. It is a saturated hydrocarbon.
Question 1.12:
What is the general formula of alkyne series ?
Solution :
B. CnH2n – 2
The general formula of the alkyne series is CnH2n – 2. It is an unsaturated hydrocarbon which has at least 2 carbon atoms combined by a triple bond.
Question 1.13:
What is the commercial name of ethyne ?
Solution :
B. Acetylene
Ethyne is an alkyne with the molecular formula C2H2. Its commercial name is acetylene.
Question 1.14:
C3H8 is the molecular formula of which compound ?
Solution :
C. Propane
C3H8 has the general molecular formula CnH2n + 2. It is an alkane with three carbon atoms. Thus, the compound with molecular formula C3H8 is propane.
Question 1.15:
What is the angle between any two bonds in methane molecule ?
Solution :
B. 109°28′
In the methane molecule, four similar orbitals of carbon have unpaired electrons and form sp3 hybridisation. The four orbitals arrange in the tetrahedral shape and form a bond angle of 109°28′.
Question 1.16:
What is called fossil fuel ?
Solution :
A. Mineral coal
Fossil fuels are natural carbon-based substances used as fuels which are formed by the remains of plants and animals over millions of years. Coal is one such substance formed over a period of millions of years.
Question 1.17:
From where mineral coal is obtained in Gujarat ?
Solution :
C. Thangadh
In Gujarat, near Thangadh in Saurashtra district, sulphur-containing mineral coal deposits are present.
Question 1.18:
What is used as fuel in jet planes ?
Solution :
C. Kerosene
Kerosene is a fuel used in households and in jet planes.
Question 2:
Answer the following questions in brief :
Question 2.1:
What is called fossil fuel and write its use.
Solution :
Fossil fuels are natural carbon-based substances used as fuel. They are formed by the remains of plants and animals over millions of years.
Uses of fossil fuels are
- As fuel for cars, trucks, aeroplanes and other vehicles and automobiles
- As power in electricity plants
- To heat or cool our homes
- To make medicines, cosmetics, plastics, synthetic fabrics and lubricants
Question 2.2:
How many main types of mineral coal are there and which are they ?
Solution :
There are four main types of mineral coal. They are
- Peat
- Lignite
- Bituminous coal
- Anthracite
Question 2.3:
Write a short note on coke.
Solution :
- Coke is obtained by the destructive distillation of mineral coal.
- It is black brown.
- It is a hard and porous substance.
- It contains about 80% of carbon.
- It is an efficient smokeless fuel.
- It is used in the production of water gas.
- It is used as a reducing agent to obtain metal from metal oxide.
Question 2.4:
Explain in brief about coal tar and coal gas.
Solution :
Coal tar:
Coal tar is a dark black liquid produced during the destructive distillation of mineral coal. It is composed of different types of organic compounds. In olden times, it was used in the preparation of organic compounds such as explosives, dyes, drugs and pesticides. Coal tar has now been replaced by petroleum products.
Coal gas:
Coal gas is a mixture of gases produced by the destructive distillation of mineral coal. Carbon monoxide plus other gaseous hydrocarbon compounds together make coal gas. It is a combustible gas and is used as a fuel.
Question 2.5:
What is the valency of carbon ? Why ?
Solution :
Carbon is tetravalent. The electronic configuration of carbon is 2, 4. It has four electrons in its valence shell. So, it has a tendency to share four more electrons to attain the octet configuration.
Question 2.6:
What is meant by hydrocarbon ? How are they classified ?
Solution :
Compounds containing hydrogen and carbon are called hydrocarbons.
Hydrocarbons are classified on the basis of the number of covalent bonds present between carbon-carbon atoms. They are classified as saturated hydrocarbons and unsaturated hydrocarbons.
Question 2.7:
Explain by drawing the shape of methane molecule.
Solution :
A methane molecule contains a carbon atom bound to four hydrogen atoms by four single covalent bonds.
Question 2.8:
From which methane is obtained ? Write its preparation
Solution :
Methane gas is prepared by heating sodium acetate and soda lime (soda lime is a 3:1 proportion mixture of sodium hydroxide and calcium oxide).
Sodium carbonate is produced as a by-product during the reaction.
Question 2.9:
Write uses of ethyne by writing its common name and structural formula.
Solution :
Uses of ethyne are
- To prepare industrially important substances such as ethanol, acetic acid, vinyl polymer and plastic
- To weld metals by using an oxyacetylene flame
- To fill rubber balloons and fly them high in the sky
Question 2.10:
What is isomerism ? Write isomers of butane and pentane.
Solution :
Organic compounds with the same molecular formula but different structural formula are called isomers. This phenomenon is called isomerism.
Isomers of butane:
Question 2.11:
The everyday life is not possible without mineral coal and petroleum. Why ?
Solution :
Humans use mineral coal for the following purposes:
- Generation of electricity
- Manufacture of cement
- Production of steel
Petroleum is used by humans in the following different ways:
- Petroleum is a source of fuel for transport.
- It is used in the production of detergents and plastics.
- Synthetic fibres and synthetic rubbers are also produced from petroleum.
- Lubrication oil produced by petroleum refining is used to make grease, Vaseline and wax.
Thus, because of the applications of petroleum products and mineral coal products in our daily life, our everyday life is not possible without mineral coal and petroleum.
Question 2.12:
Explain cracking reaction.
Solution :
The cracking reaction is a reaction which breaks organic molecules into smaller organic molecules.
For example, the cracking of kerosene to give gasolene.
In this reaction, vapours of kerosene, naphtha, diesel or wax are passed over a catalyst at 773 K. The catalyst used during these reactions is either Al2O3 or SiO2.
Apart from gasolene, methane, hydrogen and some unsaturated hydrocarbons are also obtained during the cracking reaction.
Question 3:
Answer the following questions :
Question 3.1:
Explain the destructive distillation of mineral coal in laboratory by drawing its figure.
Solution :
Destructive distillation of coal in the laboratory:
Take mineral coal in a hard glass test tube.
Take some water in another test tube.
Connect both the tubes by a bent tube as shown in the figure.
Heat the coal using a Bunsen burner.
The vapour coming out as a result of burning of coal will enter the tube containing water and will pass through it.
As a result of this, some residue gets collected at the bottom of the tube containing water. This residue is coal tar.
A gas also comes out of the tube containing water. When a lighted matchstick is brought near the end of this tube, the gas starts burning. This gas is called coal gas.
A residue is left in the hard glass test tube after complete combustion of coal. This residue is coke.
Ammonia is also formed during the distillation process. This ammonia is absorbed by water. It can be tested by inserting a red litmus paper in water. The water turns red litmus blue.
Question 3.2:
Write the types of mineral coal, explain that the use of anthracene coal is more than the bitumen coal. Why ?
Solution :
The types of mineral coal are
- Peat
- Lignite
- Bituminous coal
- Anthracite
Bituminous coal contains about 78-86% carbon, whereas anthracite contains about 94-98% carbon. Bituminous coal also contains volatile matter and moisture in proportions higher than those in anthracite coal. Moreover, when pure anthracite coal is burnt, smoke or smell is not produced. Hence, the use of anthracite coal is more than that of bituminous coal.
Question 3.3:
Explain occurrence of methane and its preparation.
Solution :
Occurrence of methane:
- Methane is a chief constituent of marsh gas.
- It is available from mines of mineral coal and gas collected over petroleum in sedimentary rocks.
- Methane is also a chief constituent of biogas prepared from dung, excretion of animals and sewage.
Preparation of methane:
Methane gas is prepared by heating sodium acetate and soda lime (soda lime is a 3:1 proportion mixture of sodium hydroxide and calcium oxide).
Sodium carbonate is produced as a by-product during the reaction.
Question 3.4:
Writing the common molecular formulas of alkanes, alkenes and alkynes, write the names of first compound of each.
Solution :
Common molecular formula | First compound | |
Alkanes | CnH2n + 2 | Methane |
Alkenes | CnH2n | Ethene |
Alkynes | CnH2n – 2 | Ethyne |
Question 4:
Answer the following questions in detail :
Question 4.1:
Explain preparation of ethene in laboratory by drawing figure.
Solution :
Ethene can be prepared in the laboratory in the following manner:
Take 3 ml of kerosene or molten wax and about one teaspoon of sand in a test tube.
Attach the test tube to the clamp in the slanting position as shown in the figure.
Add few pieces of china clay or porcelain in the front part of the test tube.
First, heat the porcelain pieces. As it turns red hot, heat the mixture of kerosene and sand.
Continue this alternate heating.
Vapours of alkene are formed; they then pass through the pieces of porcelain and liberate ethene by a cracking reaction.
The gas is collected in a gas jar by the downward displacement of water.
Question 4.2:
Explain preparation of ethyne in laboratory by drawing figure.
Solution :
Ethyne gas can be prepared in the laboratory by the reaction of calcium carbide with water.
- Take a conical flask and put few pieces of calcium carbide in it.
- Attach a thistle funnel and a bent tube to the conical flask and arrange it as shown in the figure.
- Add water to the conical flask through the thistle funnel.
- Water reacts with calcium carbide and ethyne gas is produced.
CaC2 + H2O → C2H2 + Ca(OH)2
- Collect the ethyne gas in a gas jar by the downward displacement of water.
Question 4.3:
What is meant by hydrocarbons ? Explain its classification in detail.
Solution :
Compounds containing hydrogen and carbon are called hydrocarbons.
Hydrocarbons are classified on the basis of the number of covalent bonds present between carbon-carbon atoms. They are classified as saturated hydrocarbons and unsaturated hydrocarbons.
- Saturated hydrocarbons:
Hydrocarbons in which all four valences of carbon are completed by a single covalent bond with other atoms are called saturated hydrocarbons.
For example, alkanes are saturated hydrocarbons.
- Unsaturated hydrocarbons:
Hydrocarbons in which two or more carbon atoms are combined by a double or triple covalent bond are called unsaturated hydrocarbons.
For example, alkenes and alkynes are unsaturated hydrocarbons.
Question 4.4:
Explain in detail about natural gas.
Solution :
- Natural gas is a fossil fuel collected over petroleum in rocks.
- While drilling the Earth’s crust for petroleum, natural gas is obtained first and then petroleum.
- Natural gas can also be obtained as an oily liquid along with petroleum.
- Methane is the chief component of natural gas.
- Other hydrocarbons such as ethane, propane and butane are also present in natural gas.
- Natural gas can easily be transported through pipelines and be made available as a household fuel.
- LPG and CNG are known natural gases widely used as fuels.
- Natural gas is also a source for the production of hydrogen gas on a large scale. Ammonia and urea are useful by-products during this production.
Question 5:
Answer the following question pointwise.
Question 5.1:
What is meant by petroleum ? Explain in detail the refining of petroleum.
Solution :
Petroleum is a mineral oil formed from the fossils of plants and animals buried under the surface of the Earth millions of years ago. The pressure, heat and microorganisms present at the bottom of the Earth played an important role for the formation of petroleum.
Petroleum is obtained by intensive drilling in the region of sedimentary rocks. It is a dark brown or black-coloured oily liquid which contains hydrocarbons and oxygen and sulphur containing organic compounds.
Petroleum obtained from wells is in the impure form and is further refined for purification.
At the first step, natural gas is separated from petroleum. Then the oil is allowed to settle in large tanks and waste and water are removed. The oil is then subjected to fractional distillation.
During fractional distillation, the oil is heated in a furnace and then sent to a fractionating column in the form of vapour as shown in the figure.
The fractionating column is 2 to 4 metres in diameter and 30 to 60 metres high.
In the fractionating column, perforated shelves with a cap-like cover are fixed. The vapour of the petroleum rises, and as it rises in the column, it gets cooled and comes down in the form of liquid. Thus, a dense contact between the vapour and the liquid is established. This vapour gets collected on the shelves. Substances with a higher boiling point come down in the form of liquid, and substances with a lower boiling point go up in the form of vapour.
Distillation occurs in this manner near each shelf and the compounds with different boiling points can be separated.
Thus, substances with lower boiling points are collected in the upper shelves and those having higher boiling points are collected in the lower shelves of the fractionating column. The shelves in the fractionating column are arranged such that certain fractions are collected in the shelves at certain heights. The different fractions obtained by fractional distillation of petroleum are
- Petroleum gas
- Gasoline
- Kerosene
- Gas oil/diesel oil
- Lubricating oil
- Asphalt and coke