Map Work Class 12th Geography ( Book : India - People and Economy )

 

MAP WORK Class 12th (As prescribed by  CBSE for session 2020-21)

Dear Students, 

You should download these maps and practice them on blank political outlined maps of India. The more your practice , the better skilled you will be at map work.  

Class 11th Geo Minerals and Rocks

Chapter 5 Minerals and Rocks 

 Which one of the following are the two main constituents of granite? 

(a) Iron and nickel (b) Iron and silver (c) Silica and aluminium (d) Iron Oxide and potassium 

Which one of the following is the salient feature of metamorphic rocks? 

(a) Changeable (b) Quite (c) Crystalline (d) Foliation 

Which one of the following is not a single element mineral? 

(a) Gold (b) Silver (c) Mica (d) Graphite 

Which one of the following is the hardest mineral? 

(a) Topaz () Diamond (c) Quartz (d) Feldspar

Which one of the following is not a sedimentary rock?
(a) Tillite (b) Borax (c) Breccia (d) Marble

What do you mean by rocks? Name the three major classes of rocks.
Answer:
The earth’s crust is composed of rocks. A rock is made up by aggregate of one or more minerals. Rock may be hard or soft and in varied colors. For example, granite is hard, soapstone is soft. Gabbro is black and quartzite can be milky white. Rocks do not have a definite composition of mineral constituents. Feldspar and quartz are the most common minerals found in rocks.
There are many different kinds of rocks which are grouped under three families on the basis of their mode
of formation.
They are:  Igneous Rocks  Sedimentary Rocks and Metamorphic Rocks

What is an igneous rock? Describe the method of formation and characteristics of igneous rock.
Answer:
The igneous rocks are formed when magma cools and solidifies. Igneous rocks form out of magma and lava from the interior of the earth, therefore, they are known as primary rocks.

Method of formation: When magma in its upward movement cools and turns into solid form it is called igneous rock. The process of cooling and solidification can happen in the earth’s crust or on the surface of the earth. Igneous rocks are classified based on texture. The texture depends upon the size and arrangement of grains or other physical conditions of the materials. If molten material is cooled slowly at great depths, mineral grains may be very large. Sudden cooling (at the surface) results in small and smooth grains. Intermediate conditions of cooling would result in intermediate sizes of grains making up igneous rocks. Granite, gabbro, pegmatite, basalt, volcanic breccia and tuff are some of the examples of igneous rocks.

Features:

• They are made up of solidified lava.
• Liquid lava gets solidified by gradual cooling
• They are compact
• They do not have fossils.

Define the term ‘mineral’ and name the major classes of minerals with their physical characteristics.
Answer:
A mineral is a naturally occurring organic and inorganic substance, having an orderly atomic structure and a definite chemical composition and physical properties. A mineral is composed of two or more elements. But, sometimes single element minerals like sulphur, copper, silver, gold, graphite etc. are found. There are at least 2,000 minerals that have been named and identified in the earth crust; but almost all the commonly occurring ones are related to six major mineral groups that are known as major rock forming minerals.
Some major minerals and their characteristics:

• Feldspar: Silicon and oxygen are common elements in all types of feldspar and sodium, potassium, calcium, aluminium etc. are found in specific feldspar variety.
• Quartz: It is one of the most important components of sand and granite. It consists of silica. It is a hard mineral virtually insoluble in water.
• Pyroxene: Pyroxene consists of calcium, aluminum, magnesium, iron and silica. Pyroxene forms 10 per cent of the earth’s crust.
• Amphibole: Aluminium, calcium, silica, iron, magnesium are the major elements of amphiboles. They form 7 percent of the earth’s crust.
• Mica: It comprises of potassium, aluminium, magnesium, iron, silica, etc. It forms 4 per cent of the earth’s crust.
• Olivine: Magnesium, iron and silica are major elements of olivine. It is used in jewellery. It is usually a greenish crystal, often found in basaltic rocks.
• Metallic Minerals: These minerals contain metal content and can be sub-divided into three types:
• Precious metals,
• Ferrous metals
• Non- ferrous metals.

What are metamorphic rocks? Describe the types of metamorphic rock and how are they formed?
Answer:
The word metamorphic means ‘change of form’. These rocks form under the action of pressure, volume and temperature (PVT) changes. Metamorphism takes place when rocks are forced down to lower levels by tectonic processes or when molten magma rising through the crust comes in contact with the crustal rocks or the underlying rocks are subjected to great amounts of pressure by overlying rocks. Metamorphism is a process by which already consolidated rocks undergo recrystallisation and reorganisation of materials within original rocks.
Mechanical disruption and reorganisation of the original minerals within rocks because of breaking and crushing without any appreciable chemical changes is called dynamic metamorphism. The materials of rocks chemically alter and recrystallise due to thermal metamorphism.

There are two types of thermal metamorphism:

1. Contact metamorphism: In contact metamorphism the rocks come in contact with hot intruding magma and lava and the rock materials recrystallise under high temperatures. Quite often new materials form out of magma or lava are added to the rocks.

2. Regional metamorphism: In regional metamorphism, rocks undergo recrystallisation due to deformation caused by tectonic shearing together with high temperature or pressure or both.

During metamorphism in some rocks grains or minerals get arranged in layers or lines. Such an arrangement of minerals or grains in metamorphic rocks is called foliation or lineation. Sometimes minerals or materials of different groups are arranged into alternating thin to thick layers appearing in light and dark shades. Such a structure in metamorphic rocks is called banding and rocks displaying banding are called banded rocks. Types of metamorphic rocks depend upon original rocks that were subjected to metamorphism. Metamorphic rocks are classified into two major groups foliated rocks and non-foliated rocks. Gneissoid, granite, syenite, slate, schist, marble, quartzite etc. are some examples of metamorphic rocks.

Igneous rocks act as a source of all other types of rocks. Justify.
Answer:
Yes, it is right to say that igneous rocks act as a source of all other rocks. Therefore these are also called primary rocks.
Igneous rocks are primary rocks and other rocks i.e. sedimentary and metamorphic formed from these primary rocks. Igneous rocks can be changed into metamorphic rocks. The fragments derived out of igneous and metamorphic rocks form into sedimentary rocks. Sedimentary rocks themselves can turn into fragments and the fragments can be a source for formation of sedimentary rocks. The crustal rocks (igneous, metamorphic and sedimentary) once formed may be carried down into the mantle (interior of the earth) through subduction process (parts or whole of crustal plates going down under another plate in zones of plate convergence) and the same melt down due to increase in temperature in the interior and turn into molten magma, the original source for igneous rocks.

Metallic minerals are more useful as compared to non metallic minerals. Do you agree? Justify your answer.

Answer:
No, I do not agree. Minerals both metallic and non metallic have their own importance.
1. Metallic minerals: These minerals contain metal content and can be sub-divided into three types:

• Precious metals: Gold, Sivler, Platinum, etc
• Ferrous metals: Iron, Nickel, Chromite, Maganese
• Non-ferrous metals: Copper, Lead, Zinc, Tin etc.

2. Non metallic minerals: These minerals do not have a metal content. Sulphur, phosphates and nitrates are some of the examples. Cement is a mixture of non metallic mineral. These minerals have their own utility. We can’t manage without these minerals.

Very Short Answer Type Questions

Question 1.
What does Pyroxene consists of? What percent of the earth does it occupy? What kind of colour it has?
Answer:
Pyroxene consists of calcium, aluminum, magnesium, iron and silica. Pyroxene forms 10 per cent of the earth’s crust. It is in green or black colour.

Question 2.
What does Amphibole consists of? What percent of the earth does it occupy? What kind of colour it has? Where is it used?
Answer:
Aluminium, calcium, silica, iron, magnesium are the major elements of amphiboles. They form 7 per cent of the earth’s crust. It is in green or black colour and is used in asbestos industry.

Question 3.
What are the important elements of the crust of the earth?
Answer:
About 98 percent of the total crust of the earth is composed of eight elements like oxygen, silicon, aluminium, iron, calcium, sodium, potassium and magnesium, and the rest is constituted by titanium, hydrogen, phosphorous, manganese, sulphur, carbon, nickel and other elements.

Question 4.
What do you mean by cleavage?
Answer:
The tendency to break in given directions producing relatively plane surfaces is called cleavage.

Question 5.
What do you mean by fracture?
Answer:
Internal molecular arrangement is sc complex that there are no planes o molecules; the crystal will break in an irregular manner, not along planes of cleavage.

Question 6.
What does Feldspar consists of? What percent of the earth does it occupy? What kind of colour it has? Where is it used?
Answer:
Silicon and oxygen are common elements in all types of feldspar and sodium, potassium, calcium, aluminium etc. are found in specific feldspar variety. Half of the earth’s crust is composed of feldspar. It has light cream to salmon pink colour. It is used in ceramics and glass making.

Question 7.
What is petrology?
Answer:
It is science of rocks. A petrologist studies rocks in all their aspects viz., mineral composition, texture, structure, origin, occurrence, alteration and relationship with other rocks.

Question 8.
Give some examples of igneous rocks.
Answer:
Granite, gabbro, pegmatite, basalt, volcanic breccia and tuff are some of the examples of igneous rocks.

Question 9.
What is rock cycle?
Answer:
Rock cycle is a continuous process through which old rocks are transformed into new ones.

Question 10.
What is Quartz? Give some of its features.
Answer:
It is one of the most important components of sand and granite. It consists of silica. It is a hard mineral virtually insoluble in water. It is white or colourless and used in radio and radar. It is one of the most important components of granite.

Question 11.
What is the form of inner and outer form of the earth?
Answer:
The interior most part of the earth is in liquid form but its uppermost layer is in the form of solid.

Question 12.
What is the root source of all types of rocks?
Answer:
Magma which is found in the interior of the earth is the root source of all minerals.

Question 13.
Give one example of solid, liquid and gaseous form of minerals.
Answer:
Solid form of minerals is coal, liquid form is petroleum and diesel and gaseous form is natural gas.

Question 14.
What does mica consists of? What per cent, of the earth crust consists of mica? In which type of rocks is it found? Where is it used?
Answer:
It comprises of potassium, aluminium, magnesium, iron, silica etc. It forms 4 per cent of the earth’s crust. It is commonly found in igneous and metamorphic rocks. It is used in electrical instruments.

Question 15.
What are non-metallic minerals? Give examples.
Answer:
These minerals do not contain metal content. Sulphur, phosphates and nitrates are examples of non-metallic minerals. Cement is a mixture of non- metallic minerals.

Question 16.
What does Olivine consists of? In which type of rocks is it found?
Answer:
Magnesium, iron and silica are major elements of olivine. It is used in jewellery. It is usually a greenish crystal, often found in basaltic rocks.

Question 17.
What are the root sources of igneous rocks?
Answer:
Magma is the root source of igneous rocks. The igneous rocks are formed when magma cools and solidifies. When magma in its upward movement cools and turns into solid form it is called igneous rock. The process of cooling and solidification can happen in the earth’s crust or on the surface of the earth.

Question 18.
How does systematic formation of minerals take place?
Answer:
The basic source of all minerals is the hot magma in the interior of the earth. When magma cools, crystals of minerals appear and a systematic series of minerals are formed in sequence to solidify so as to form rocks.

Question 19.
What kind of qualities do minerals have?
Answer:
A mineral is a naturally occurring organic and inorganic substance having an orderly atomic structure and a definite chemical composition and physical properties for example sulphur, copper, silver, and gold, etc.

Question 20.
Name the minerals which are single elements?
Answer:
Sulphur, copper, silver, gold, graphite are single elements.

Class 12th Geo Chapter 12 GEOGRAPHICAL PERSPECTIVE ON SELECTED ISSUES AND PROBLEMS

 Chapter 12 GEOGRAPHICAL PERSPECTIVE ON SELECTED ISSUES AND PROBLEMS

Assignment Dated 10.08.2020
Which one of the following river is highly polluted?
(a) Brahmaputra
(b) Satluj
(c) Yamuna
(d) Godavari
Which one of the following diseases is caused by water pollution?
(a) Conjunctivitis
(b) Diarrhorea
(c) Respiratory infections
(d) Bronchitis
Which one of the following is the cause of acid rain?
(a) Water pollution
(b) Land pollution
(c) Noise pollution
(d) Air pollution
Push and pull factors are responsible for-
(a) Migration
(b) Land degradation
(c) Slums
(d) Air pollution
 “Indiscriminate use of water by increasing population and industrial expansion has led to degradation of the quality of water considerably.” Evaluate the statement.
Answer - Increasing population and industrial expansion are responsible for water pollution:

·        Domestic and sewage waste water remains untreated.

·        Excessive use of fertilizers and pesticides in farming results in water pollution.

·        Cultural activities: fairs, tourism, pilgrimage, etc.

·        Industries produce many undesirable substances which pollutes water.

·        Chemical residues and toxins pollute water.

·        Major polluting industries are leather, pulp, paper, textiles, chemicals, etc.

 

“Air pollution is very harmful to flora, fauna and property.” Explain any three values which can help in maintaining pollution free air to some extent.
Answer:
Values which can help in maintaining pollution free air:

·        Air pollution is harmful for environment and mankind, therefore, it is our responsibility to save air from pollution.

·        People should be aware of the harmful effects of air pollution.

·        People should feel duty bound to save air.

·        People must follow rules for saving air.

·        We must use eco friendly non-conventional sources of energy (Solar, Biogas and Wind energy) as conventional sources (Coal, oil and gas) are harmful.

·        People should feel duty bound to use public transport.

Describe any three major problems of slums in India

·        Their houses are dillapidated and poor hygienic conditions.

·        They have lack basic amenities like drinking water, light and toilet facilities.

·        These areas are over croweded having narrow street pattern prone to serious hazard from fire.

What is criterion for the classification of pollution?
Answer:
Different types of pollution are classified on the basis of medium through which pollutants are transported and diffused.

Examine any three causes for the deterioration of quality of water in India.
Answer -

·        Water gets polluted by foreign matters like chemicals, industrial waste etc.

·        Various types of chemicals used in modern agriculture such as inorganic fertilisers, pesticides, etc. are also pollution generating components.

·        Cultural activities such as pilgrimage, religious fairs also cause water pollution.

 

 

Explain three ill effects of air pollution on human health in India.

Answer

·        It causes various disease related to respiratory system, nervous and circulatory systems.

·        It causes smoky fog over cities called as urban smog which is very harmful to us.

·        It causes acid rain etc.

How has noise pollution become hazardous in many big cities of India? Explain with example.
Answer

·        Traffic noise is the biggest sources of air pollution as its intensity and nature depend upon the type of aircraft, vehicle, train and the condition of road.

·        In sea traffic, the noise pollution is confined to the harbour due to loading and unloading of goods being carried, (in) Noise pollution’s intensity declines with increase in distance from the source of pollution, i.e., industrial areas, arteries of transportation, airport, etc.

Explain any two major sources of air pollution in India? How is the air pollution harmful to human health?
Answer
Two major sources of air pollution in India are: Combustion of coal, petrol and diesel, mining, solid waste disposal, sewage, vehicles etc.
Effect of air pollution on human are:

·        It causes various disease related to respiratory system, nervous and circulatory systems.

·        It causes smoky fog over cities called as urban smog which is very harmful to us.

·        It causes acid rain etc.

What are the major features of slums in India?

1.       Slums are least choice residential areas that have broken down house, bad hygienic conditions, poor ventilation and does not have basic facilities like drinking water, light and toilet facilities, etc.

2.     Slums are overcrowded with people and have many narrow street patterns prone to serious hazards from fire.

3.     Most of the slum dwellers works for low wages, high risk-prone and unorganised sectors of the urban economy.

4.     They face various health related problems such as malnutrition, illness and prone to various diseases. They are not able to send their children school to provide them education because of low level of income.

5.     Dwellers are vulnerable to drug abuse, alcoholism, crime, vandalism, escapism, apathy and social exclusion because of poverty.

Urbanization is a big factor in the pollution levels rising globally. What are the major trends and statistics of urbanization in the world?

1 Currently, about 54% of the world’s 7 billion (2011) population lives in urban areas of world . This proportion of urban population will increase in future.

2 It is estimated that between 2025 to 2030, this percentage would be grown with 1.44% per year. This high urban population will pressurise governments to optimise infrastructure facilities in urban areas for giving a standard quality of life.

3 It is estimated that by 2050, about two-thirds of the world’s population will live in urban areas. It would create a high pressure on existing infrastructure and sanitation, health, crime problems and urban poverty.
4 There are various factors responsible for growth of urban population:

     A - When high birth rate and low morality rate increase.

B - Net in-migration or movement of people from other areas.

C - Reclassification of urban areas to encompass formerly rural settlements.

5 In India there is a estimation that about 60% India’s urban population has increased after 1961. About 29% of this growth has been caused by rural-urban migration.

Discuss the problems caused by poor solid waste management.

1.       Solid wastes are threat to human health and can cause various diseases. It creates foul smell and it harbours flies and rodents that can cause typhoid, diphtheria, diarrhoea, malaria, cholera and other diseases.

2.     Solid waste can create inconvenience rapidly if they are not properly handled. Wind and rain water can splitted it and cause a discomfort to people.

3.     Industrial solid waste can cause water pollution by dumping it into water bodies. Drains carrying untreated sewage also result into various health problems.

4.     Untreated waste release various poisonous biogases such as methane in air by slow fermentation process. These wastes are resources as energy can be generated from them! By compositing these wastes, problem of energy could be solved as well as its management in urban areas.

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Blog Creation Steps (continued)

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continued



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