Test: Soil, Rocks & Minerals - 2 - Class 5 MCQ

Answer:
Introduction:
In this question, we are asked to name an igneous rock that is smooth, glassy, and used in making jewelry.

The correct answer is Obsidian. Here are the reasons why:
- Smooth and Glassy: Obsidian is a type of volcanic glass that forms when molten lava cools rapidly. Its smooth and glassy texture makes it ideal for crafting jewelry.
- Igneous Rock: Obsidian is an igneous rock, which means it is formed from solidified molten material (magma or lava).
- Jewelry: Due to its attractive appearance and unique properties, obsidian is often used in making jewelry. It can be cut and polished into various shapes and sizes, making it suitable for necklaces, pendants, earrings, and other accessories.
- Properties: Obsidian is known for its shiny, reflective surface and is usually black in color. However, it can also occur in other colors such as brown, green, or red, depending on the impurities present.
- Other Uses: Apart from jewelry, obsidian is also used for making sharp cutting tools, mirrors, and as an abrasive material in industries.
Conclusion:
Obsidian is an igneous rock that is smooth, glassy, and commonly used in making jewelry. Its attractive appearance and unique properties make it a popular choice for crafting various accessories.

Answer:
The correct answer is C: Molten.
Explanation:
The Earth is composed of several layers, including the crust, mantle, and core. However, "Molten" is not a layer of the Earth. Here is a breakdown of the Earth's layers:
1. Crust: This is the outermost layer of the Earth, which is divided into two types: continental crust and oceanic crust. It is the thinnest layer, ranging from 5 to 70 kilometers in thickness.
2. Mantle: The mantle lies beneath the crust and extends to a depth of about 2,900 kilometers. It is composed of solid rock but can flow slowly over long periods of time. The mantle is further divided into the upper mantle and the lower mantle.
3. Core: The core is the innermost layer of the Earth and is divided into two parts: the outer core and the inner core. The outer core is liquid, consisting mainly of molten iron and nickel, while the inner core is solid due to higher pressure.
Therefore, the correct answer is C: Molten, as it is not a recognized layer of the Earth.

Answer:
Coal is a kind of sedimentary rock that is made of plant remains buried under the earth.
Explanation:
- Coal is formed from the remains of plants that lived and died millions of years ago.
- These plants were buried under layers of sediment and subjected to heat and pressure over time.
- The process of coal formation is known as coalification.
- As the plant material is buried deeper and deeper, it undergoes chemical and physical changes, resulting in the formation of coal.
- The carbon content in coal gives it its characteristic black color.
- Coal is primarily composed of carbon, along with various other elements such as hydrogen, oxygen, nitrogen, and sulfur.
- It is a combustible rock and is widely used as a source of energy for electricity generation and industrial processes.
- Different types of coal exist, including anthracite, bituminous coal, and lignite, depending on their carbon content and energy value.
In conclusion, coal is a sedimentary rock that is formed from the remains of plant material, making it the correct answer for the given question.

Non-Metallic Mineral: Mica
- Mica is a non-metallic mineral and is the correct answer to the given question.
- Non-metallic minerals are those minerals that do not have metallic properties and are not used as a source of metal or for metallurgical extraction.
- Mica is a group of minerals that have perfect basal cleavage, are highly flexible, and have high electrical and thermal conductivity.
- It is commonly used in electrical and electronic industry as an insulating material, in paint, cosmetics, and plastic industries, and also in the production of roofing materials and decorative items.
- Mica is an important mineral in various industries due to its unique physical and chemical properties.

Answer:
Explanation:
The correct answer is D: All the above. All of the options listed (Granite, Obsidian, and Pumice) are types of igneous rocks. Here is a brief description of each:
- Granite: Granite is a common type of igneous rock that is composed mainly of quartz, feldspar, and mica. It is known for its durability and is often used in construction and as a decorative stone.
- Obsidian: Obsidian is a volcanic glass that forms when molten lava cools rapidly. It is usually black in color and has a smooth, glassy texture. Obsidian is often used in jewelry and as a cutting tool.
- Pumice: Pumice is a light-colored, porous igneous rock that forms from volcanic eruptions. It is filled with small gas bubbles, which give it its characteristic lightweight and abrasive texture. Pumice is commonly used as a scrubbing stone and in horticulture.
In conclusion, all of the options provided (Granite, Obsidian, and Pumice) are examples of igneous rocks.

Answer:
The correct answer is Quartzite. Quartzite is a metamorphic rock that forms from the metamorphosis of sandstone. Here is a detailed explanation:
Metamorphism:
Metamorphism is the process by which rocks undergo changes in mineralogy, texture, or chemical composition due to high temperatures and pressures. It occurs deep within the Earth's crust, usually in regions of tectonic activity.
Sandstone:
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains. It is formed by the deposition and lithification of sand particles.
Metamorphosis of Sandstone:
When sandstone undergoes metamorphism, it transforms into a new rock called quartzite. This transformation occurs due to the recrystallization of the sand grains under high temperatures and pressures. The original sand grains fuse together, and the rock becomes more compact and hard.
Characteristics of Quartzite:
- Quartzite is composed primarily of quartz, which is a mineral made up of silicon and oxygen.
- It has a granular texture and often exhibits a sugary appearance.
- Quartzite is usually light-colored, ranging from white to gray, but it can also occur in shades of pink, red, or yellow.
- It is a very hard and durable rock, making it suitable for various construction purposes.
Other Options:
- Slate: Slate is a metamorphic rock formed from the metamorphosis of shale or mudstone, not sandstone.
- Minerals: Minerals are not rocks but are naturally occurring substances with a defined chemical composition and crystal structure.
- Wood: Wood is an organic material derived from plants and is not formed by the metamorphosis of sandstone.
In conclusion, the rock formed by the metamorphosis of sandstone is Quartzite.

Flint is a type of rock that falls under the category of Sedimentary rocks.
Explanation:
- Flint is a hard, sedimentary form of cryptocrystalline quartz, also known as chert.
- Sedimentary rocks are formed through the accumulation and consolidation of sediments, which can include fragments of minerals, rocks, and organic matter.
- Flint is typically formed from the remains of marine organisms such as microscopic algae or sponge spicules that accumulate on the ocean floor over time.
- These organic material-rich sediments undergo compaction and lithification, resulting in the formation of flint.
- Flint is known for its characteristic smooth, glassy appearance and its ability to produce sparks when struck against steel, making it a valuable material for tools and fire-making in ancient times.
- Other examples of sedimentary rocks include limestone, sandstone, and shale.
Therefore, the correct answer is B: Sedimentary.

The mineral used in making chalk is Gypsum. Here is a detailed explanation:
- Chalk is primarily composed of calcium carbonate, but it also contains small amounts of other minerals that give it its unique properties.
- Gypsum is one of the minerals commonly found in chalk. It is a soft sulfate mineral composed of calcium sulfate dihydrate.
- Gypsum is widely used in various industries, including the production of chalk.
- It is ground into a fine powder and mixed with water to form a paste, which is then shaped into sticks or molded into the desired shape.
- When the chalk paste dries, it hardens and forms the familiar white sticks or pieces of chalk that we use for writing or drawing.
- Gypsum provides the necessary binding properties to hold the chalk together and gives it a smooth texture.
- Apart from its use in making chalk, gypsum is also used in construction, agriculture, and as a soil conditioner.
- Other minerals listed as options in the question, including Fluorine, Mica, and Feldspar, do not have a direct role in the production of chalk.
Therefore, the correct answer is C: Gypsum.

Rocks are made up of minerals.
Explanation:
Rocks are naturally occurring solid substances that are composed of minerals or mineral-like materials. Here is a detailed explanation:
- Definition of rocks: Rocks are aggregates of minerals or mineraloids. They are classified based on their mineral and chemical composition, texture, and origin.
- Minerals: Minerals are naturally occurring inorganic substances with a specific chemical composition and a crystalline structure. They are the building blocks of rocks.
- Composition of rocks: Rocks are made up of different combinations of minerals. They can contain one dominant mineral or a mixture of several minerals.
- Types of rocks: There are three main types of rocks based on their origin: igneous, sedimentary, and metamorphic.
- Igneous rocks: These rocks are formed from the solidification of molten material, either from volcanic eruptions or solidification beneath the Earth's surface. Examples include granite and basalt.
- Sedimentary rocks: These rocks are formed from the accumulation and compaction of sediments, such as sand, mud, and organic remains. Examples include limestone and sandstone.
- Metamorphic rocks: These rocks are formed by the transformation of pre-existing rocks through heat and pressure. Examples include marble and slate.
- Rock cycle: Rocks can undergo changes through the rock cycle, which involves processes like weathering, erosion, deposition, and metamorphism. This cycle allows rocks to transform from one type to another over long periods of time.
In conclusion, rocks are made up of minerals, which are naturally occurring inorganic substances with a specific chemical composition and crystalline structure. The different types of rocks are defined by their mineral composition and how they are formed.

Scientist who studies rocks is known as a geologist.

• Zoologist: A scientist who studies animals.


• Ornithologist: A scientist who studies birds.


• Geologist: A scientist who studies rocks, minerals, and the Earth's crust.


• Chemist: A scientist who studies the composition, properties, and reactions of substances.


• None of these: None of the given options are correct.

Therefore, the correct answer is Option C: Geologist.

Answer:
Explanation:
Metamorphic rocks are formed as a result of the transformation of an existing rock due to heat and pressure. Here is a detailed explanation:
1. Metamorphic Rocks:
- Metamorphic rocks are rocks that have undergone changes in their mineralogy, texture, or chemical composition due to heat and pressure.
- These changes occur deep within the Earth's crust where the rocks are subjected to high temperatures and pressures.
- Examples of metamorphic rocks include marble, slate, gneiss, and quartzite.
2. Formation of Metamorphic Rocks:
- Metamorphic rocks are formed from pre-existing rocks, which can be igneous, sedimentary, or even other metamorphic rocks.
- The existing rock, called the parent rock or protolith, undergoes changes in response to heat and pressure.
- The heat and pressure cause recrystallization of minerals, resulting in the formation of new minerals and a change in the rock's texture and structure.
- The transformation can occur due to regional metamorphism (large-scale tectonic forces) or contact metamorphism (localized heating by a nearby magma intrusion).
3. Distinguishing Features:
- Metamorphic rocks often exhibit foliation, which is a parallel alignment of minerals or mineral bands.
- They can also contain minerals that are not found in the parent rock.
- The texture of metamorphic rocks can range from fine-grained to coarse-grained, depending on the degree of metamorphism.
In conclusion, rocks formed as a result of the transformation of an existing rock due to heat and pressure are called metamorphic rocks.

Explanation:
The correct answer is C: Coal.
Reason:
Fossil fuels are formed from the remains of ancient plants and animals. They are called "fossil" fuels because they are formed over millions of years by the pressure and heat from the Earth's crust.
Key Points:
- Fossil fuels are non-renewable resources.
- They release carbon dioxide and other greenhouse gases when burned, contributing to climate change.
- Coal, oil, and natural gas are the three major types of fossil fuels.
- Coal is a black or brownish-black sedimentary rock that is primarily composed of carbon.
- It is formed from the remains of plants that lived and died millions of years ago.
- Coal is used as a fuel primarily for electricity generation and industrial processes.
Summary:
Among the options given, coal is the only fossil fuel. Iron, aluminium, and copper are metals, and none of them are fossil fuels.

Answer: Shale
Explanation:
- Shale is a sedimentary rock that is commonly used in making bricks and cement.
- It is composed primarily of clay minerals and has a fine-grained texture.
- Shale is easily broken into thin layers or flakes, making it suitable for brick production.
- It can also be crushed and mixed with other materials to produce cement.
- Shale is abundant and widely distributed, making it a cost-effective and sustainable option for construction materials.
- Other sedimentary rocks like conglomerate, sandstone, and limestone are not typically used in making bricks and cement.
- Conglomerate is composed of rounded pebbles and is not easily broken into thin layers.
- Sandstone is composed of sand-sized particles and is often used as a building material, but not specifically for bricks and cement.
- Limestone is primarily composed of calcium carbonate and is commonly used as a building material, but not specifically for making bricks and cement.

When magma cools slowly under the ground, it forms:
- Granite: Granite is a type of igneous rock that forms from the slow cooling and solidification of magma deep underground. It is composed mainly of quartz and feldspar minerals.
- Shale: Shale is a type of sedimentary rock that forms from the accumulation of clay and silt particles. It does not form directly from the cooling of magma.
- Marble: Marble is a metamorphic rock that forms from the recrystallization of limestone or dolomite. It does not form directly from the cooling of magma.
- Sandstone: Sandstone is a type of sedimentary rock that forms from the accumulation and cementation of sand grains. It does not form directly from the cooling of magma.
- None of these: The correct answer is option A, granite, as it is the type of rock that forms when magma cools slowly under the ground.
Explanation:
- Magma is molten rock that is found beneath the Earth's surface.
- When magma cools slowly, it has more time to crystallize, resulting in the formation of larger mineral grains.
- Granite is a coarse-grained igneous rock that forms from slowly cooled magma deep underground.
- The slow cooling allows the minerals in the magma to grow and interlock, giving granite its characteristic coarse texture and visible mineral grains.
- Other rocks like shale, marble, and sandstone form through different processes and are not formed directly from the cooling of magma.
- Therefore, the correct answer is option A, granite.

The mineral that is used to produce nuclear energy is Uranium. Here is a detailed explanation:
- Nuclear energy is generated through a process called nuclear fission, where the nucleus of an atom is split into two smaller nuclei.
- Uranium is a radioactive element that undergoes nuclear fission easily, making it an excellent fuel source for nuclear power plants.
- When uranium atoms are bombarded with neutrons, they split into smaller atoms, releasing a significant amount of energy in the process.
- This energy is harnessed and used to heat water and produce steam, which drives turbines to generate electricity.
- Uranium is abundant in nature and can be found in various regions around the world, including Canada, Australia, and Kazakhstan.
- It is extracted from the earth through mining processes and then processed to obtain a concentrated form of uranium known as uranium ore.
- The uranium ore is further refined to remove impurities and increase its concentration of uranium-235, the isotope primarily used in nuclear reactors.
- The enriched uranium is then formed into fuel pellets, which are loaded into fuel rods and placed inside the reactor core of a nuclear power plant.
- As the uranium atoms split, they release more neutrons, which can initiate a chain reaction, resulting in a continuous release of energy.
- The controlled chain reaction in a nuclear reactor allows for the sustained production of nuclear energy.
In summary, uranium is the mineral that is used to produce nuclear energy due to its ability to undergo nuclear fission and release a significant amount of energy.

Explanation:
- Petroleum is a complex mixture of hydrocarbons, and it is used as a raw material to produce various products.
- Let's analyze each option to determine which one is not obtained from petroleum:
- Plastic: Plastic is derived from petroleum through a process called polymerization. It is one of the major products obtained from petroleum.
- Candle: Candles are usually made from wax, which can be derived from petroleum.
- Pumice stone: Pumice stone is a volcanic rock that is formed during volcanic eruptions. It is not derived from petroleum.
- Paint: Paints contain pigments, binders, solvents, and other additives. Some of these components can be derived from petroleum.
- Therefore, the correct answer is C: Pumice stone as it is not obtained from petroleum.
- All the other options, A, B, and D, are obtained from petroleum in some way or another.
- Hence, the correct answer is option C: Pumice stone.

Answer:
Gemstones
- Gemstones are naturally occurring minerals that are cut and polished to be used in jewelry or other decorative items.
- They are valued for their beauty, rarity, and durability.
- Gemstones can be classified into different categories based on their chemical composition, color, and other physical properties.
Options:
A: Sapphire
- Sapphire is a gemstone that belongs to the corundum mineral family.
- It is typically blue in color, but can also occur in other colors such as pink, yellow, and green.
- Sapphire is known for its hardness and brilliance, making it a popular choice for jewelry.
B: Topaz
- Topaz is another gemstone that is often used in jewelry.
- It is a silicate mineral and is commonly found in yellow or brown colors, although it can occur in other colors as well.
- Topaz is known for its clarity and luster.
C: Steel
- Steel is not a gemstone.
- It is an alloy of iron and carbon, commonly used in the construction and manufacturing industries.
Correct Answer:
D: Both [a] and [b]
- Both Sapphire and Topaz are gemstones.
Incorrect Answer:
E: None of these
- This answer is incorrect as both Sapphire and Topaz are gemstones.
In conclusion, the correct answer is D: Both [a] and [b], as both Sapphire and Topaz are gemstones. Steel, on the other hand, is not a gemstone.

Sulphates are used as:
A: Fuels
- Sulphates are not used as fuels. They do not have the necessary properties to serve as a source of energy.
B: Fertilizers
- Sulphates are commonly used as fertilizers in agricultural practices.
- They provide essential nutrients such as sulphur and sulphate ions, which are vital for plant growth.
- Sulphates can be used in both organic and inorganic fertilizers.
C: Gemstones
- Sulphates are not used as gemstones.
- Gemstones are typically minerals or rocks that are valued for their beauty and rarity, and sulphates do not fall into this category.
D: Building materials
- Sulphates are not commonly used as building materials.
- Building materials are typically substances like concrete, steel, wood, and bricks, which have structural properties. Sulphates do not possess these properties.
E: None of these
- The correct answer is option B, sulphates are used as fertilizers.
In summary, sulphates are primarily used as fertilizers in agriculture. They provide essential nutrients for plant growth and are not used as fuels, gemstones, or building materials.

Answer:
Explanation:
The correct answer is option D: All the above. All the options mentioned (Gold, Silver, and Aluminium) are metallic minerals. Here is a detailed explanation:
Definition of Metallic Minerals:
Metallic minerals are minerals that contain metal elements in their chemical composition and have industrial uses. These minerals are usually hard, opaque, shiny, and have good electrical and thermal conductivity.
Explanation of Options:
- Gold: Gold is a metallic mineral. It is a precious metal known for its rarity and beauty. Gold is widely used in jewelry, dentistry, electronics, and as a form of currency.
- Silver: Silver is also a metallic mineral. It is a lustrous white metal with excellent electrical and thermal conductivity. Silver is used in jewelry, photography, electrical contacts, and various industrial applications.
- Aluminium: Aluminium is a metallic mineral as well. It is a lightweight, silvery-white metal with good strength and corrosion resistance. Aluminium is used in various industries, including transportation, construction, packaging, and electrical applications.
Conclusion:
All the options mentioned in the question (Gold, Silver, and Aluminium) are metallic minerals. Therefore, the correct answer is option D: All the above.

Explanation:
The correct answer is B: Igneous rocks.
Definition:
Igneous rocks are formed when molten rocks, known as magma or lava, cool down and solidify.
Process:
1. Magma is formed deep within the Earth's crust or mantle through the melting of pre-existing rocks.
2. When the temperature of the magma decreases, it begins to cool down and solidify.
3. As the magma cools, mineral crystals start to form, and the rock hardens.
4. The rate of cooling determines the size of the mineral crystals in the igneous rock. Slow cooling allows larger crystals to form, while rapid cooling results in smaller crystals or even a glass-like texture.
Types of Igneous Rocks:
1. Intrusive Igneous Rocks: These rocks form when magma cools slowly beneath the Earth's surface. Examples include granite and gabbro.
2. Extrusive Igneous Rocks: These rocks form when lava cools quickly on the Earth's surface. Examples include basalt and obsidian.
Other Options:
- Metamorphic rocks: These rocks are formed by the transformation of pre-existing rocks due to high heat and pressure. They do not involve the cooling and solidification of molten rocks.
- Sedimentary rocks: These rocks are formed through the accumulation and lithification of sediments. They are not directly formed from the cooling of molten rocks.
Therefore, the correct answer is B: Igneous rocks.