7 ROCKS AND MINERALS - Testlabz · Ans. Earthworm helps to keep the soil fertile by their burrowing...

1Class-VI Chemistry Question Bank

7 ROCKS AND MINERALSI. Multiple choice questions: Tick ( ) the correct choice.

1. A mineral made of atoms of simple element is(a) sand, (b) quartz (c) gold (d) clay

2. The rock formed by the cooling of magma under the surface of earthis(a) basalt (b) granite (c) limestone (d) haematite

3. The example of sedimentary rock is(a) granite (b) basalt (c) limestone (d) marble

4. The example of metamorphic rock is(a) basalt (b) dolomite (c) marble (d) shale

5. The hardest gemstone is(a) ruby (b) sapphire (c) black diamond (d) emerled

6. Cuprite is an ore of(a) aluminium (b) iron (c) copper (d) calcium

7. Symbiotic bacteria are formed in the roots of(a) cereal plants (b) pod bearing plants(c) cotton plants (d) none of these

8. A mineral from which a metal can be profitably extracted is called(a) ore (b) basalt (c) magma (d) granite

9. Limestone and marble are rich in(a) mica (b) sand (c) calcium (d) quartz

10. Pudding stone is the name given to(a) conglomerate (b) quartzite(c) basalt (d) tuff

11. The earth crust is made up of(a) rocks (b) mineral(c) silicon and aluminium (d) all the above

12. Scientists who study about rocks and the crust of the earth are called(a) zoologists (b) geologists(c) paleontologists (d) none of these

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13. During volcanic eruptions, this molten material is continually ejectedto the surface of the earth:(a) Magma (b) Lava (c) Volcanic ash (d) Pumice

14. Which one of these is formed from the foam on the top of the lavastream when lava cools down quickly?(a) Pumice (b) Obsidian (c) Basalt (d) Tuff

15. Which one of these is present in granite rock?(a) Amethyst (b) Garnet (c) Malachite (d) Ruby

16. Taj Mahal is made up of(a) white granite (b) calcium carbonate(c) sandstone (d) slate

17. Minerals make up(a) rocks (b) elements(c) substances (d) metallurgy

Ans. 1. (c) 2. (b) 3. (c) 4. (c) 5. (c) 6. (c) 7. (b) 8. (a) 9. (c) 10. (a)11. (d) 12. (b) 13. (a) 14. (a) 15. (b) 16. (b) 17. (a).

II. Define these terms.1. Mineral 2. Sedimentary rock 3. Igneous rock 4. Metamorphic rock 5.

Fossil fuel 6. Magna 7. Ore 8. Erosion 9. Non-renewable sources ofenergy.

1. Mineral: Minerals are naturally occurring inorganic substanceswhich may be made of single element or more than one element.

2. Sedimentary rock: The rocks formed by the decomposition ofparticles (sediments) by the flowing water or blowing wind are calledsedimentary rocks.

3. Igneous rocks: The rocks formed by the cooling and solidification ofextremely hot motion materials of the earth are called igneous rocks.

4. Metamorphic rocks: The rocks formed by the intense heat andpressure on the sedimentary rocks, such that their structure andtexture changes are called metamorphic rocks.

5. Fossil fuel: Fuels which are preserved in the earth’s crust as remainsof dead plants and animals are called fossil fuels.

6. Magma: The extremely hot molten material within the interior of theearth, which is under high pressure, is called magma.


7. Ore: A mineral from which a metal can be extracted profitably iscalled an ore.

8. Erosion: The loss of the topmost layer of soil by the action of windand water is called erosion.

9. Non-renewable sources of energy: The sources of energy whichcannot be produced again within a reasonable span of time are callednon-renewable sources of energy.

III. Write short notes on the following.1. Properties of minerals 2. Tuff 3. Grems 4. Quazite

Ans. Properties of minerals:(a) Minerals have a definite chemical composition.(b) Each mineral has a characteristic crystalline structure.(c) Sometimes, a mineral can have two or more different crystalline

structures depending upon how they are formed in nature.(d) Minerals have a characteristic lustre, colour, hardness and

specific gravity.2. Tuff: Sometimes lava is ejected out of a volcano with such a force that

it goes high up into the air which hardens into small pieces of rockbefore it reaches the ground. Sometimes, these are cemented togetherto form a solid rock. The rock formed in this way is dull grey. It iscalled tuff.

3. Gems: Precious stones found in rocks, like garnet in granite rock, arecalled gems. They are used in jewellery because of their brilliance andcolour.

4. Quartize. Sandstones gradually change to quartzite. It is so hard thatpaving stones are sometimes made of it.

IV. Complete the following sentences with appropriate terms/phrases:a. The scientists who study rocks are called _______ .b. The nature of the magma determines the _______ .c. The largest deposits of sediments can be found in the _______ .d. Metals that occur in minerals in the form of elements are called

_______ .e. Constant exposure to wind and rain causes soil _______ .f. Decayed organic material found in soil is called _______ .

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Ans. a. Geologists b. kind of igneous rocks c. river or seabeds d. nativeelements e. erosion f. humus.

V. Match the following rocks / minerals with their uses:(a) Granite (i) Diamonds(b) Limestone (ii) Plaster of Paris(c) Kimberlite (iii) Building material(d) Slate (iv) Cement(e) Gypsum (v) Silicon chips(f) Quartz (vi) Roofs

Ans. a. (iii) b. (iv) c. (i) d. (vi) e. (ii) f. (v)VI. Give four examples for each of the following:

(a) Igneous rocks (b) Sedimentary rocks (c) Metamorphic rocks(d) Precious stones (e) Semi-precious stones.

(a). Igneous rocks: Granite, basalt, pumice and obsidian.(b). Sedimentary rocks: Sandstone, dolomite, shale and limestone.(c). Metamorphic rocks: Marble, slate, quartzite and gneiss.(d). Precious stones: Diamond, ruby, sapphire and emeralds.(e). Semi-precious stones: Agate, tiger’s eye, amethyst and rose quartz.

VII. Differentiate between:(i) Metamorphic and igneous rocks (ii) Soil and sediments (iii) Coal and

petroleum (iv) Clay and sand(i) The rocks formed by the cooling and solidification of extremely hot

molten materials of the earth are called igneous rocks while the rocksformed by the intense heat and pressure on the sedimentary rocks,such that their structure and texture changes are called metamorphicrocks.

(ii) Soil is the uppermost layer of land mass, which acts as a supportingmedium for the growth of plants while the particles which aredeposited from one place to another by the action of wind or waterare called sediments.

(iii) Coal and Petroleum: Coal is formed when huge forest areas gotburied under the surface of the earth by the action of anaerobicbacteria while petroleum is formed by the anaerobic decomposition


of extremely small sea animals and plants which got buried under thesurface of the earth.

(iv) Clay particles are below 0.002 mm in size, have very little air and canhold a large amount of water. Size of sand particles is between 0.02mm to 0.20 mm. They have very large amount of air and cannot holdwater.

VIII. Give reasons:(a) Igneous rocks are used extensively for construction purpose.

Ans. Igneous rocks are very hard. Hence, they are used extensively forconstruction purposes.

(b) Wide areas of rock changed when mountains were formed.Ans. In areas of extreme temperature, where hot day temperatures are

followed by cold night temperatures, it leads to crack in rocks. Inareas of cold temperature, water that seeps into the cracks freezes. Aswater expands on freezing, it widens the crack. Thus, wide areas ofrock changed and mountains were formed.

(c) Earthworms are called nature’s gardeners.Ans. Earthworm helps to keep the soil fertile by their burrowing which

aerates the soil. So, earthworms are called nature’s gardeners.(d) Coal and petroleum are non-renewable sources of energy.

Ans. There is only a limited supply of coal and petroleum in nature. Oncethey are used up, they cannot be replaced. So, they are called non-renewable sources of energy.

IX. Match the statements in Column A with Column B.

Column A Column B1. An ore of aluminium metal. (a) Haematite2. An ore of iron metal. (b) Bauxite3. A mineral from which a metal is (c) Clayey soil

extracted.4. A rock formed by the cooling of (d) Rock

magma under the surface of the earth.5. A soil containing 70% or more of clay. (e) Granite6. A black stony substance used as a fuel. (f) Weathering7. The phenomenon which results in the (g) Coal

formation of soil.

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8. A hard substance formed by the (h) Oreassembly of one or more inorganicminerals.

Ans. 1. (b) 2. (a) 3. (h) 4. (e) 5. (c) 6. (g) 7. (f) 8. (d).

X. Column A Column B1. Combination of minerals (a) organic matter2. Calcium carbonate (b) minerals3. Inorganic substances in the earth’s crust (c) marble4. Flowing magma (d) obsidian5. Humus (e) lava6. Amber rocks (f) rocks

Ans. 1. (f) 2. (c) 3. (b) 4. (e) 5. (a) 6. (d).XI. Write true or false in front of the following statements:

1. Coal is a prehistoric fuel, commonly called fossil fuel.2. Diamond is used for making jewellery.3. Granite is an example of igneous rock.4. Humus is the waste created by dead plants and has no soil value.5. Marble is a metamorphic rock.6. Clayey soils are best for agriculture.7. Soil is formed due to erosion by heat, wind and water.8. Minerals are useful compounds formed by microbes.

Ans. 1. T 2. T 3. T 4. F 5. T 6. F 7. T 8. F.XII. Write true or false for the given statements. Rewrite the false

statements correctly.1. Basalt is a coarse grained hard rock.

Ans. False. Basalt is a fine grained hard rock.2. Dolomite is formed due to the deposition of magnesium bicarbonate.

Ans. False. Dolomite is formed due to the deposition of calcium carbonateand magnesium carbonate.

3. The preserved relics of past found in igneous rocks are called fossils.Ans. False. The preserved relics of past found in sedimentary rocks are

called fossils.4. Marble is an example of sedimentary rock.


Ans. False. Marble is an example of metamorphic rock.5. Plaster of Paris is used in the manufacture of cement.

Ans. False. Lime is used in the manufacture of cement.6. Bauxite is an ore of copper.

Ans. False. Bauxite is an ore of aluminium.7. Loamy soils contain 60% – 70% of clay particles and are very

porous.Ans. False. Clayey soils contain 60% – 70% of clay particles and are not

porous.8. The size of silt particles is between 0.02 mm to 0.20 mm.

Ans. False. The size of silt particles is between 0.002 mm to 0.02 mm.9. Oxygen, silicon, aluminium and iron are the common elements

present in the hydrosphere.Ans. False. Oxygen, silicon, aluminium and iron are the common elements

present in the lithosphere.10. Metamorphic rocks are formed when layers of rock pieces and

eroded soil get squeezed together.Ans. False. Sedimentary rocks are formed when layers of rock pieces and

soil get squeezed together.11. Organic matter buried long ago under extremely high temperature and

pressure turns into coal, peat and amber.Ans. False. Organic matter buried long ago under extremely high

temperature and pressure turns into coal and petroleum.12. Granite is a common igneous rock.

Ans. True13. Bauxite is an ore of calcium.

Ans. False. Bauxite is an ore of aluminium.14. Rocks are made up of different types of minerals.

Ans. True15. All ores are minerals but all minerals are not ores.

Ans. True16. Marble is a calcium rich rock.

Ans. TrueXIII. Complete the given sentences.

1. A hard substance formed by the assembly of one or more ..................minerals, is called a rock.

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2. Shale is formed due to the .................. of fine clay.3. The extremely hot and molten material within the surface of the earth

is called .................. .4. Coal and petroleum are called .................. fuels.5. Soils having 70% – 80% of .............. particles are called sandy soils.6. .................. is an ore of copper.7. .................. are used for making expensive watches.8. .................. is used for making talcum powder.9. .................. are identified by their colour, lustre and hardness.

10. An .................. is a .................. from which one or more metals can beextracted.

11. .................. are made up of different combinations of minerals.12. Sediments are generally formed .................. .13. Granite is usually formed .................. .14. .................. is the external rock crust of the earth.15. The three types of rocks are .................. , .................. and metamorphic.16. Preserved remains of plants and animals are called ................ .17. Shale smells like .................. when wet.

Ans. 1. inorganic 2. deposition 3. magma 4. fossil 5. sand 6. Malachite7. Gems 8. Talc 9. Minerals 10. ore, mineral 11. Rocks 12. under water13. underground 14. lithosphere 15. igneous, sedimentary 16. fossils17. mud.

XIV. Find out the odd one out. Give a reason for your answer.1. Cuprite, quartz, haematite and bauxite

Ans. Haematite, bauxite and cuprite are metallic ores is while quartz is anon-metallic mineral of metamorphic rocks.

2. Shale, marble, dolomite and sandstoneAns. Shale, sandstone and dolomite are examples of sedimentary rocks

while marble is an example of metamorphic rock.3. Slate, granite, marble and quartz

Ans. Slate, marble and quartz are examples of metamorphic rocks whilegranite is an example of igneous rock.

4. Ruby, graphite, sapphire and emeraldAns. Ruby, sapphire and emerald are gemstones while graphite is not a

gemstone.


5. Sandstone, conglomerate, limestone, slate, coal and shaleAns. Sandstone, conglomerate, limestone, slate and shale are examples of

rocks while coal is a fossil fuel.6. Pumice, obsidian, basalt, tuff, coal and granite

Ans. Pumice, obsidian, basalt, tuff and granite are examples of igneousrocks while coal is an example of sedimentary rocks.

7. Slate, quartzite, marble, sandstone, schist and gemsAns. Slate, quartzite, marble, sandstone and schist are examples of

metamorphic rocks while gems are crystals of ornamental value.8. Quartz, feldspar, mica, bauxite, gypsum and talc

Ans. Feldspar, mica, quartz, gypsum and talc are non-metallic mineralswhile bauxite is a metallic ore.

9. Bauxite, pitchblende, haematite and quartzAns. Bauxite, pitchblende, and haematite are metallic ore while quartz is a

non-metallic mineral.XV. Answer the following questions :

1. (i) What is a rock?(ii) What is an igneous rock?

(iii) Briefly explain how the following rocks are formed: (a) granite(b) basalt.

Ans. (i) Rock is a hard substance formed by the assembly of one or moreinorganic minerals.

(ii) The rocks formed by the cooling and solidification of extremelyhot molten materials of the earth are called igneous rocks.

(iii) (a) Formation of granite: When the magma rising up through theinterior of the earth, solidifies beneath the surface of theearth, the coarse grained rock so formed is called granite.

(b) Formation of basalt: Basalt rock is formed from the lavawhich flows out of the surface of the earth and then coolsslowly.

2. Define sedimentary rock and give four examples.Ans. The rocks formed by the deposition of particles (sediments) by the

flowing water or blowing wind are called sedimentary rocks. Forexample, mudstone, shale, sandstone and limestone.

3. Define metamorphic rock. Give two examples of metamorphic rock.

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Ans. The rocks that are formed by the intense heat and pressure on thesedimentary rocks, such that their structure and texture changes arecalled metamorphic rocks. Slate and marble are examples ofmetamorphic rocks.

4. (i) What do you understand by the term mineral?(ii) State three characteristics of minerals.

Ans. (i) Minerals are naturally occurring inorganic substances which maybe made of atoms of a single element or more than one element,but having a definite composition.

(ii) Characteristics of minerals.1. Minerals have a definite chemical composition.2. Each mineral has a characteristic crystalline structure, which

depends upon the arrangement of atoms in three dimensionalpattern.

3. Minerals have a characteristic lustre, colour, hardness andspecific gravity.

5. (i) What is the difference between a diamond and a gem?(ii) State two uses of gems, in addition to their use as precious

stones.Ans. (i) Diamond is a transparent form of crystalline carbon. It is highly

priced and is used for making jewellery. While artificial gemscan be prepared by heating aluminium oxide to a very hightemperature. They are used in making expensive watches.

(ii) Uses of gems:(a) Gems are used in making expensive watches.(b) They are also used in laser technique.

6. (i) State any two uses of common salt.(ii) State any two uses of Plaster of Paris.

(iii) Name the mineral from which lime is prepared. State any twouses of lime.

Ans. (i) Uses of common salt:(a) Its purified form is used as table salt.(b) It is used for preserving fish, meat and also in pickles.

(ii) Uses of Plaster of Paris:(a) It is used for plastering fractured bones.(b) It is used for preparing moulds for statues.


(iii) Lime is prepared by strongly heated limestone. Uses of lime.(a) It is used for white washing purposes.(b) It is used in the manufacture of cement.

7. What do you understand by the term soil?Ans. Soil is the uppermost layer of landmass of the earth, which acts as a

life supporting medium for the growth of plants.8. Name one important ore of (a) aluminium, (b) iron, (c) copper.

Ans. (a) Bauxite is an ore of aluminium.(b) Haematite is an ore of iron.(c) Cuprite is an ore of copper.

9. Name the four important constituents of the top soil.Ans. The four important constituents of soil are:

1. Soil particles of different sizes2. Humus 3. Soil water 4. Soil air

10. Name the types of particles of soil in the decreasing order of size.Ans. The types of soil particles in the decreasing order of size are gravel,

coarse sand, fine sand, silt and clay.11. What is humus? Why is its presence important for the plants?

Ans. Humus is formed from the dead plants and animals by the activity ofmicroorganisms present in the soil. Presence of humus is importantfor plants because it contains all the nutrients which are required forthe growth of plants.

12. Briefly explain the following: (i) sandy soils, (ii) clayey soils,(iii) loamy soils.

Ans. (i) Sandy soils: Soils having 70 – 80% of sand particles are calledsandy soils. They are highly porous with a lot of air. They cannotretain water and lack humus. They are not suitable for the growthof plants.

(ii) Clayey soils: Soils having more than 70% clay particles andvery little sand particles are called clayey soils. These soils havevery little air and can hold a large amount of water. These soilsare also not much suitable for the growth of plants.

(iii) Loamy soils: These soil contain a balanced amount of clay andsand particles and contain a good amount of humus. They containa sufficient amount of air and water. These soils are best for the

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growth of plants.13. Briefly explain the importance of water soluble nitrogen compounds

in the fertility of soil.Ans. Plants need nitrogen in the form of water soluble nitrogen compounds

for the manufacture of amino acids and proteins. This proteinconstitute the protoplasm of the plant cells and help in their growthand development.

14. How does the soil get enriched with water soluble nitrogencompounds (i) in nature, (ii) with the help of farmer.

Ans. (i) Nature. Nature compensates nitrogen in two ways:(a) By thunder and lightening: When lightening occurs, nitrogen

and oxygen combine to form nitric oxide gas. This gas furtherreacts with oxygen to form nitrogen dioxide. It dissolves inwater to form nitric acid. When it rains, nitric acid is washeddown to the earth where it reacts with calcium carbonate toform calcium nitrate and hence make the soil fertile.

(b) By symbiotic bacteria: Root nodules of pod bearing plantscontain symbiotic bacteria, which directly absorb nitrogenfrom the air and convert it into soluble compounds ofnitrogen.

(ii) By farmer: Farmers supply manure and artificial fertilisers suchas urea, etc. in adequate amount to get the soil enriched withwater soluble nitrogen compounds.

15. Briefly explain how coal is formed in nature?Ans. Coal is formed from the huge forests which got buried under the

surface of the earth, under humid and hot conditions, by the action ofanaerobic bacteria.

16. Briefly explain how petroleum is formed in nature?Ans. Petroleum is formed by the anaerobic decomposition of extremely

small sea animals and plants which got buried under the surface of theearth millions of years ago.

17. Name a few problems created by the excessive use of fossil fuels.Ans. Excessive use of fossil fuels led to the increase in the amount of

carbon dioxide in the atmosphere by which theaverage temperature ofthe earth is gradually increasing. In addition to it, poisonous gases


such as nitrogen dioxide, sulphur dioxide and carbon monoxide areadded into the atmosphere which are very harmful.

18. What factors bring about changes in pre-existing rocks?Ans. Excess heat, frost, wind, high pressure and temperature, sideways

pushing and rain are some factors that bring about changes in pre-existing rocks.

19. What type of rock is basalt? Why is it used to make tools?Ans. Basalt is a type of igneous rock which is formed from the lava which

cools rather slowly. Basalt has sharp edges; so it is used to maketools.

20. What are ores? Name the ores of iron and aluminium.Ans. A mineral from which a metal can be extracted profitably is called an

ore. Bauxite is an ore of aluminium and haematite is an ore of iron.XVI. Answer in a sentence or two.

(a) How are rocks classified?Ans. Rocks are classified into igneous, sedimentary and metamorphic

rocks, based on how they are formed.(b) Mention two uses of sedimentary rocks.

Ans. Limestone and shale are example of sedimentary rocks.(i) Limestone is used for making cement.

(ii) Shale is used for making drainpipes.(c) Why are some minerals highly valued as gems?

Ans. Some minerals are extremely rare, attractive as well as durable, sothey are highly valued as gems.

(d) Name the ores from which the following metals are obtained:(i) Aluminium (ii) Copper (iii) Iron (iv) Lead

Ans. (i) Aluminium is obtained from bauxite.(ii) Copper is obtained from cuprite.

(iii) Iron is obtained from haematite.(iv) Lead is obtained from galena.

(e) What is the effect of erosion on rocks?Ans. Rocks are broken into small pieces by the action of wind, rain and

changes in temperature. This is called erosion.(f) Mention the three types of soil.

Ans. Clay, sand and loam are the three types of soil.

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(g) In which kind of rocks are fossils most likely to be found?Ans. Fossils are most likely to be found in sedimentary rocks.

(h) Why are coal and petroleum called fossil fuels?Ans. Coal and petroleum are called fossil fuels because they are formed

from the remains of plants and animals that lived million of years ago.(i) List the uses of coal and petroleum.

Ans. Coal and petroleum are major sources of energy. They are used formaking plastics, drugs, dyes and detergents.

(j) Name four renewable sources of energy.Ans. Energy from the sun, water, wind, ocean tides and waste from animals

and plants are renewable sources of energy.

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7 ROCKS AND MINERALS - Testlabz · Ans. Earthworm helps to keep the soil fertile by their burrowing...

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