NCERT TEXTBOOK QUESTIONS
Q.1. Choose the right answer from the four alternatives
given below :
(i) Minerals are deposited and accumulated in stratas of
which of the following rocks?
(a) Sedimentary rocks (b) Metamorphic rocks (c) Igneous rocks (d) None of the above
Ans. (a)
(ii) Koderma in Jharkhand is the leading producer of which
one of the following minerals?
(a) Bauxite (b) Mica (c) Iron ore (d) Copper
Ans. (b)
(iii) Which of the following minerals is contained in the Monazite sand?
(a) Oil (b) Uranium (c) Thorium (d) Coal
Ans. (c)
(iv) Which one of the following mineral ores is formed by
decomposition of rocks, leaving a residual mass of weathered materials?
(a) Coal (b) Bauxite (c) Gold (d) Zinc
Ans. (b)
Q.2. Answer the following questions briefly.
(i) Distinguish between ferrous and non-ferrous minerals.
Give examples.
Ans. Metallic minerals can be classified into ferrous and
non-ferrous minerals.
Ferrous Minerals
(i) Metallic minerals containing iron are called
ferrous minerals.
(ii) They account for about three-fourths of
the total value of production of metallic
minerals in India.
(iii) Iron ore, manganese, chromite, tungsten,
nickel and cobalt are examples of ferrous
minerals.
Non-Ferrous Minerals
Metallic minerals that contain metals other than
iron are non-ferrous minerals.
India’s
reserves and production of non-ferrous
minerals is not very satisfactory.
copper, lead, tin, bauxite, gold are examples of
non-ferrous minerals as they do not contain iron.
Conventional Sources
of Energy Non-conventional
Sources of Energy
1. Conventional sources of energy have been 1. Non-conventional sources have been put to
in use since time immemorial. use in the recent past.
2. Most of them, especially the fossil fuels are 2. They are inexhaustible, renewable resources.
limited and exhaustible.
3. They emit smoke and ash on burning and 3. They are environment friendly as they do not cause cause environmental pollution. pollution.
4. As the supply fossil fuels are limited they 4. As they are flow resources, freely found in nature
are expensive. in abundance, they are less expensive.
5. Simple mining as well as modern 5. Advanced scientific technology is involved
technology are involved in their production. in its production.
6. Coal, mineral oil, natural gas, and hydel 6. Solar energy, wind energy, tidal energy,
power are examples of conventional geothermal energy, biogas and energy from
sources of energy. urban waste are examples of non-conventional
sources of energy.
(ii) What are minerals? How are they classified?
Ans. Minerals are natural resources which are obtained from
rocks. Geologists define a mineral as a “homogeneous, naturally occurring substance with a
definable internal structure.” They are normally found in solid, liquid and gaseous states. They
have a definite chemical composition and crystalline structure. A particular mineral that will be
formed from a single or certain combination of elements depends upon the physical and
chemical conditions under which the material forms. Minerals are classified into metallic and
non-metallic minerals and energy resources.
(iii) How are minerals formed in ingeous and metamorphic rocks ?
Ans. In igneous and metamorphic rocks minerals may occur in the cracks, crevices, faults or joints. The smaller occurances are called veins and the larger are called the lodes. In most cases, they are formed when minerals in liquid/molten and gaseous forms are forced upward through cavities towards the earth's surface. they cool and solidify as they rise.
(iv) Why do we need to conserve mineral resources ?
Ans. The total volume of workable mineral deposites is an insignificant fraction i.e. one percent of the earth's crust. We are rapidly consuming mineral resources that required million of years to be created and concentrated. The geological processes of mineral formation are so slow that the rates of replenishment are infinitely small in comparison to the present rates of consumption. Mineral resources are therefore, finite and non-renewable. Rich mineral deposits are our country's extremely valuable but short lived possessions. Continued extraction of ores leads to increasing costs as mineral extraction comes from greater depths along with decrease in quality.
Q.3. Answer the following questions in about 120 words.
(i) Describe the Distribution of coal in India.
Ans. The major resources of metallurgical coal belong to the
Gondwana age and are located mainly in the north eastern part of the peninsula. Rich
reserves of coal are found in the Damodar Valley region in the states of West
Bengal and Jharkhand. Raniganj in West Bengal and Jharia and
Bokaro in Jharkhand are important coalfields. One third of the total production comes from here.
Coal is also found in the Godavari, Mahanadi,
Son and Wardha valleys. Korba in Chhattisgarh, Singrauli and Penah-kanhan valley in Madhya
Pradesh, Talcher in Orissa, Kamptee and Chandrapur in Maharashtra
and Singareni of Andhra Pradesh are important coal mines. Tertiary coal occur in the north eastern states of Meghalaya, Assam,
Arunachal Pradesh and Nagaland. Principal lignite reserves are found in Neyveli in Tamil
Nadu.
(ii) Why do you think that Solar energy has a bright future in India ?
The western parts of India, especially the Thar deserts
region, receive undisturbed sunshine for most parts of the year. This area has great potential
for development of energy and can be utilised as the largest solar power house of India.
Solar energy is becoming fast popular in different parts of
the country, especially in rural and remote areas. It can be used for cooking, heating of
water, pumping, refrigeration, street lighting and room heating in cold areas. The largest
solar plant of India
is located at Madhapur near Bhuj in Gujarat.
The solar energy is used to sterilise milk cans.
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