Worksheet Solutions: Minerals and Rocks | Geography Class 11 - Humanities/Arts PDF Download

Fill in the Blanks

Q1: A mineral is a naturally occurring __________ and inorganic substance.
Ans: inorganic
A mineral is indeed naturally occurring, but it should be inorganic, not organic.

Q2: Some single-element minerals include __________ and gold.
Ans: sulphur
Single-element minerals refer to minerals composed of a single chemical element.

Q3: The most abundant elements in the Earth's crust are oxygen, silicon, __________, and iron.
Ans: aluminum
The correct spelling is "aluminium," and these are indeed some of the most abundant elements in the Earth's crust.

Q4: The basic source of all minerals is the __________ in the interior of the Earth.
Ans: hot magma
Minerals form from the cooling and crystallization of molten magma within the Earth.

Q5: When magma cools and solidifies, it forms __________.
Ans: igneous rocks
This is a fundamental process in the formation of igneous rocks.

Q6: Cleavage is the tendency of a mineral to break along specific __________.
Ans: planes
Cleavage is indeed the property of breaking along specific planes of weakness within a mineral.

Q7: __________ is the appearance of a material without regard to color.
Ans: Luster
Lustre refers to how a mineral reflects light, regardless of its color.

Q8: Streak is the color of the ground powder of a mineral when it is __________.
Ans: scratched on a porcelain plate
This answer correctly explains that the streak is the color of a mineral's powdered form, and it may differ from the mineral's actual color.

Q9: Transparent minerals allow __________ to pass through.
Ans: light
Transparency is the property of allowing light to pass through, making objects visible.

Q10: Petrology is the scientific study of __________.
Ans: rocks
Petrology indeed is the scientific study of rocks.

Assertion and Reason Based

Q1: Assertion: Quartz is a hard mineral virtually insoluble in water.
Reason: Quartz is composed of calcium and aluminum.
(a) If both the assertion and reason are true and the reason is a correct explanation of the assertion.
(b) If both the assertion and reason are true but the reason is not a correct explanation of the assertion.
(c) If the assertion is true, but the reason is false.
(d) If both the assertion and reason are false.
Ans: (c)
The assertion is true as quartz is hard and virtually insoluble in water. However, the reason is false; quartz is composed of silicon and oxygen, not calcium and aluminum.

Q2: Assertion: Metamorphism occurs due to pressure, volume, and temperature changes.
Reason: Dynamic metamorphism involves appreciable chemical changes.
(a) If both the assertion and reason are true and the reason is a correct explanation of the assertion.
(b) If both the assertion and reason are true but the reason is not a correct explanation of the assertion.
(c) If the assertion is true, but the reason is false.
(d) If both the assertion and reason are false.
Ans: (b)
Both the assertion and reason are true. Metamorphism is caused by pressure, volume, and temperature changes, and dynamic metamorphism involves mechanical disruption without appreciable chemical changes.

Q3: Assertion: Igneous rocks are classified based on texture.
Reason: Sudden cooling results in large mineral grains in igneous rocks.
(a) If both the assertion and reason are true and the reason is a correct explanation of the assertion.
(b) If both the assertion and reason are true but the reason is not a correct explanation of the assertion.
(c) If the assertion is true, but the reason is false.
(d) If both the assertion and reason are false.
Ans: (b)
The assertion is true; igneous rocks are classified based on texture. However, the reason is not entirely correct, as sudden cooling can result in small and smooth grains, not large grains.

Q4: Assertion: Sedimentary rocks can be classified into mechanically formed, organically formed, and chemically formed.
Reason: Sedimentary rocks form from the cooling of magma.
(a) If both the assertion and reason are true and the reason is a correct explanation of the assertion.
(b) If both the assertion and reason are true but the reason is not a correct explanation of the assertion.
(c) If the assertion is true, but the reason is false.
(d) If both the assertion and reason are false.
Ans: (c) If the assertion is true, but the reason is false.
The assertion is true, but the reason is false. Sedimentary rocks form from the lithification of sediments, not the cooling of magma.

Q5: Assertion: The crustal rocks can be carried down into the mantle through the subduction process.
Reason: The mantle is located on the Earth's surface.
(a) If both the assertion and reason are true and the reason is a correct explanation of the assertion.
(b) If both the assertion and reason are true but the reason is not a correct explanation of the assertion.
(c) If the assertion is true, but the reason is false.
(d) If both the assertion and reason are false.
Ans: (d) If both the assertion and reason are false.
Both the assertion and reason are false. The mantle is beneath the Earth's crust, not on the surface.

Very Short Answer Type Questions

Q1: What is the composition of feldspar?
Ans: Feldspar is composed of aluminum silicates combined with potassium, sodium, or calcium.

Q2: What is the primary source of all minerals?
Ans: The primary source of all minerals is the Earth's crust.

Q3: Name one mineral that can be found in solid, liquid, and gaseous forms.
Ans: Water is one mineral that can be found in solid (ice), liquid (water), and gaseous (water vapor) forms.

Q4: Define cleavage in minerals.
Ans: Cleavage in minerals refers to the tendency of a mineral to break along specific flat surfaces, producing smooth and flat fragments.

Q5: Give an example of a non-metallic mineral.
Ans: Quartz is an example of a non-metallic mineral.

Q6: What is the process of rocks breaking up into various-sized fragments due to denudational agents?
Ans: The process of rocks breaking up into various-sized fragments due to denudational agents is called weathering.

Q7: Name one rock that is classified as an igneous rock.
Ans: Granite is an example of an igneous rock.

Q8: What is the word used to describe the change of form in rocks?
Ans: The word used to describe the change of form in rocks is metamorphism.

Q9: How do sedimentary rocks form?
Ans: Sedimentary rocks form through the accumulation and lithification (compaction and cementation) of sediments.

Q10: What is the parent material of soils derived from?
Ans: Soils are derived from the parent material, which is the underlying rock or sediment that weathers and undergoes soil formation.

Short Answer Type Questions

Q1: Explain the difference between cleavage and fracture in minerals.
Ans: Cleavage in minerals refers to their tendency to break along specific planes of weakness, resulting in flat, smooth surfaces. Fracture, on the other hand, occurs when the mineral lacks distinct planes of weakness, leading to irregular and jagged breaks.

Q2: Describe the process of lithification in sedimentary rock formation.
Ans: Lithification is the process by which sediments are deposited, compacted, and turned into sedimentary rocks. It involves the compaction of loose sediments and the binding of the particles together.

Q3: Discuss the three major groups of sedimentary rocks based on their mode of formation.
Ans: Sedimentary rocks are classified into mechanically formed (e.g., sandstone), organically formed (e.g., limestone), and chemically formed (e.g., halite) based on the processes of their formation. Mechanically formed rocks result from the physical breakdown and transport of particles. Organically formed rocks are created from the accumulation of organic materials. Chemically formed rocks originate from the precipitation of minerals from water.

Q4: What are the major types of metamorphism, and how do they differ?
Ans: Metamorphism is the process by which rocks undergo changes in mineral composition, texture, and structure due to pressure, temperature, and other factors. Dynamic metamorphism involves mechanical changes without significant chemical alteration, while thermal metamorphism occurs due to changes in temperature, and pressure. In contact metamorphism, rocks are altered by contact with hot magma, and in regional metamorphism, rocks are subjected to heat and pressure on a large scale.

Q5: Explain how the rock cycle works and the transformations rocks undergo.
Ans: The rock cycle is a continuous process where rocks are transformed from one type to another. Igneous rocks can be changed into metamorphic rocks through heat and pressure. The weathering of igneous and metamorphic rocks creates sediments, which can form sedimentary rocks. Over time, these rocks may be subducted into the mantle and melted to create new igneous rocks.

Q6: Give examples of precious metals and non-ferrous metals found in metallic minerals.
Ans: Precious metals like gold, silver, and platinum are valuable because of their rarity and economic significance. Ferrous metals include iron and steel. Non-ferrous metals, such as copper, lead, zinc, tin, and aluminum, do not contain iron.

Q7: Explain the difference between foliated and non-foliated metamorphic rocks.
Ans: Foliated metamorphic rocks have a layered or banded appearance due to the alignment of mineral grains. Non-foliated metamorphic rocks lack this layered structure. Examples of foliated rocks include schist and slate, while marble and quartzite are non-foliated.

Q8: How are minerals and rocks significant in a geographer's study of the Earth's surface?
Ans: Geographers study rocks to understand their role in landforms, soil composition, and the Earth's history. Rocks influence the type of soil in a region, and understanding the distribution of different rock types helps geographers explain the Earth's physical features.

Long Answer Type Questions

Q1: Discuss the physical characteristics of minerals, including color, luster, hardness, and cleavage, with examples.
Ans: Minerals are naturally occurring inorganic solids with a specific chemical composition and a crystalline structure. They exhibit various physical characteristics that can be used to identify and classify them.

• Color: Color is one of the most noticeable characteristics of minerals. However, it is not always a reliable indicator as many minerals can occur in different colors. For example, quartz can be found in various colors such as clear, white, pink, purple, and even black.
• Luster: Luster refers to the way light interacts with the surface of a mineral. It can be classified into metallic and non-metallic luster. Minerals like pyrite and galena exhibit metallic luster, while minerals like quartz and feldspar have non-metallic luster.
• Hardness: Hardness is a measure of a mineral's resistance to scratching. The Mohs scale of hardness is commonly used to determine the hardness of minerals. For example, talc has a hardness of 1, while diamond has a hardness of 10.
• Cleavage: Cleavage refers to the way a mineral breaks along planes of weakness due to its crystal structure. It is described by the number of cleavage directions and the angles between them. For instance, mica has one perfect cleavage, resulting in thin sheets, while feldspar exhibits two cleavage directions at nearly right angles.

Examples of minerals with these characteristics include:

• Color: Quartz (various colors), Calcite (colorless, white, yellow, pink, etc.)
• Luster: Pyrite (metallic), Talc (non-metallic)
• Hardness: Feldspar (6-6.5), Diamond (10)
• Cleavage: Mica (one perfect cleavage), Halite (three cubic cleavages)
  
  

Q2: Describe the major minerals and their characteristics, focusing on feldspar, quartz, pyroxene, amphibole, mica, and olivine.
Ans:

• Feldspar: Feldspar is a group of minerals that are the most abundant in the Earth's crust. They are characterized by their hardness (6-6.5 on the Mohs scale), two cleavage directions at nearly right angles, and a non-metallic luster. Feldspar is commonly found in igneous, metamorphic, and sedimentary rocks.
• Quartz: Quartz is a mineral composed of silicon and oxygen atoms. It is known for its hardness (7 on the Mohs scale), a wide range of colors, and a glassy or vitreous luster. Quartz has no cleavage and fractures conchoidally. It is a common mineral in many rock types and is also found in various forms such as amethyst and citrine.
• Pyroxene: Pyroxene is a group of dark-colored minerals that are commonly found in igneous and metamorphic rocks. They have a prismatic crystal habit, two cleavage directions at approximately 90 degrees, and a vitreous to dull luster. Common pyroxene minerals include augite and diopside.
• Amphibole: Amphibole minerals are another group of dark-colored minerals commonly found in igneous and metamorphic rocks. They have a prismatic crystal habit, two cleavage directions at approximately 60 and 120 degrees, and a vitreous to dull luster. Common amphibole minerals include hornblende and actinolite.
• Mica: Mica is a group of minerals known for their perfect cleavage, resulting in thin, flexible sheets. They have a pearly to vitreous luster and come in various colors such as white, brown, and green. Mica minerals are commonly found in metamorphic rocks and are used in various industrial applications.
• Olivine: Olivine is a green-colored mineral that is commonly found in igneous rocks such as basalt and peridotite. It has a glassy luster, conchoidal fracture, and no cleavage. Olivine is a major component of the Earth's mantle and is also found in meteorites.
  
  

Q3: Explain the classification of rocks based on their mode of formation, discussing igneous, sedimentary, and metamorphic rocks in detail.
Ans: 

• Igneous Rocks: Igneous rocks are formed from the solidification of molten rock material, either magma or lava. They can be further classified into two types:
  • Extrusive Igneous Rocks: These rocks form when lava cools and solidifies on the Earth's surface. The rapid cooling results in fine-grained texture, and examples include basalt and rhyolite.
  • Intrusive Igneous Rocks: These rocks form when magma cools and solidifies beneath the Earth's surface. The slow cooling process allows for larger crystal growth, resulting in coarse-grained texture. Examples include granite and gabbro.
• Sedimentary Rocks: Sedimentary rocks are formed from the accumulation and consolidation of sediments, which are derived from the weathering and erosion of pre-existing rocks. They can be further classified into three types:
  • Clastic Sedimentary Rocks: These rocks are formed from the compaction and cementation of rock fragments or grains. Examples include sandstone, shale, and conglomerate.
  • Chemical Sedimentary Rocks: These rocks are formed from the precipitation of minerals from a solution. Examples include limestone, gypsum, and rock salt.
  • Organic Sedimentary Rocks: These rocks are formed from the accumulation of organic remains, such as shells or plant matter. Examples include coal and chalk.
• Metamorphic Rocks: Metamorphic rocks are formed from the transformation of pre-existing rocks due to high temperatures, pressures, or chemical changes. They can be further classified into two types:
  • Foliated Metamorphic Rocks: These rocks have a layered or banded appearance due to the alignment of mineral grains. Examples include slate, schist, and gneiss.
  • Non-foliated Metamorphic Rocks: These rocks do not have a layered or banded appearance and are characterized by interlocking mineral grains. Examples include marble and quartzite.
    
    

Q4: Elaborate on the rock cycle and how it relates to the transformation of rocks from one type to another. Include the role of igneous rocks in this cycle.
Ans: The rock cycle is a continuous process that describes the formation, breakdown, and reformation of rocks. It involves various geological processes and occurs over millions of years. The rock cycle consists of three main types of rocks: igneous, sedimentary, and metamorphic.
The cycle begins with the formation of igneous rocks through the solidification of molten rock material, either magma or lava. This process is called crystallization. Igneous rocks can be further weathered and eroded by natural forces such as wind, water, and ice, leading to the formation of sediments.
These sediments undergo compaction and cementation, resulting in the formation of sedimentary rocks. This process is known as lithification. Sedimentary rocks can also be subjected to heat and pressure, which leads to their transformation into metamorphic rocks. This process is called metamorphism.
Metamorphic rocks can then be uplifted to the Earth's surface through tectonic forces or erosion, where they can undergo weathering and erosion, starting the cycle again. Alternatively, they can be subjected to melting due to increased heat and pressure, forming magma and initiating the formation of igneous rocks.
Igneous rocks play a crucial role in the rock cycle as they provide the starting point for the formation of other rock types. Through weathering and erosion, igneous rocks are broken down into sediments, which can then be transported, deposited, and lithified into sedimentary rocks. Additionally, igneous rocks can also be subjected to metamorphism, resulting in the formation of metamorphic rocks.
Overall, the rock cycle demonstrates the interconnectedness and constant transformation of rocks from one type to another, driven by geological processes such as heat, pressure, weathering, and erosion.