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Bangla GK Mock Test Set - 21

Raghu Sir ডিসেম্বর ০৭, ২০২৪

 


Quiz
10:00

1. which of the following is the primary ore of aluminium:









Correct Answer: A) Bauxite
  • Bauxite is the primary source of aluminium and is extensively mined in countries like Australia and Guinea.
  • Aluminium is extracted from bauxite through a process called the Bayer process.
  • Bauxite typically contains 30%–60% aluminium oxide (Al2O3).
  • It is also used in producing refractory materials and as an abrasive.
  • Bauxite was first discovered in 1821 in Les Baux, France, from where it gets its name.
  • Globally, aluminium is the second-most-used metal after steel.

    • 2. The element which is found in the highest concentration in Earth's rocks and minerals is:









    Correct Answer: B) Silicon
  • Silicon makes up about 27.7% of Earth's crust by mass and is the second most abundant element after oxygen.
  • It is a key component in many minerals, including quartz and various types of silicates.
  • Silicon is widely used in technology, particularly in semiconductors and solar cells.
  • Though abundant, pure silicon is rarely found in nature; instead, it is commonly found in combination with oxygen.
  • Silicon plays a significant role in rock formation, particularly in igneous and sedimentary rocks.
  • It also has various industrial applications, from construction materials to electronics.

    • 3. An alloy commonly used in the production of heating elements for electric devices is:









    Correct Answer: A) Nichrome
  • Nichrome is an alloy consisting mainly of nickel and chromium.
  • It is known for its high resistance to oxidation and high temperatures, making it ideal for heating elements.
  • Applications of nichrome include heating elements in toasters, hairdryers, and industrial furnaces.
  • It can sustain temperatures of up to 1,200°C without melting, which is critical in heating applications.
  • Nichrome's resistance increases with temperature, which allows it to maintain its durability during heating.
  • It is also used in fireworks for ignition systems because of its heat-resistant properties.

    • 4. German silver is an alloy composed of:









    Correct Answer: A) Zinc, Copper, and Nickel
  • Despite its name, German silver contains no silver. Instead, it is an alloy of copper, zinc, and nickel.
  • It has a silvery appearance, which is why it is often used in the manufacture of cutlery, musical instruments, and decorative items.
  • German silver was originally named for its widespread use in Germany during the 19th century.
  • The alloy is highly resistant to corrosion, making it useful in marine and architectural applications.
  • It is often used as a base for silver plating in items like tableware and jewelry.
  • German silver has a high tensile strength, which also makes it suitable for making mechanical parts and springs.

    • 5. Match the following metals with their corresponding ores:









    Correct Answer: A) 4, 3, 1, 2
  • Aluminium is primarily extracted from Bauxite, while Uranium comes from Pitchblende.
  • Thorium is obtained from Monazite, which is a major source of thorium in India.
  • Lead is extracted from Galena, which is one of the most common lead minerals found.
  • Knowing the correct metal-ore pairings is important in the field of metallurgy.
  • These minerals are processed to extract the corresponding metal for industrial and commercial use.
  • The identification of ores is crucial for mining and extracting metals efficiently.

    • 6. Diamond is an allotropic form of:









    Correct Answer: A) Carbon
  • Diamond is one of the allotropes of carbon, the other being graphite.
  • Diamond's structure consists of carbon atoms arranged in a crystal lattice, giving it exceptional hardness.
  • It is the hardest naturally occurring substance and is widely used in cutting and drilling tools.
  • Diamonds are also valued as gemstones for jewelry due to their brilliance and rarity.
  • Graphite, another allotrope of carbon, has a layered structure and is soft, making it ideal for use in pencils.
  • The difference between graphite and diamond is due to the way carbon atoms are bonded in their structures.

    • 7. Air is classified as:









    Correct Answer: A) Mixture
  • Air is a mixture of gases, primarily nitrogen (78%) and oxygen (21%), along with trace amounts of other gases like argon and carbon dioxide.
  • It is not a compound because the gases are not chemically bonded, they simply coexist.
  • Air also contains water vapor, dust particles, and various pollutants, which contribute to its mixture properties.
  • Being a mixture, the composition of air can vary depending on location and altitude.
  • Air is essential for respiration, combustion, and other processes that sustain life on Earth.
  • In industrial settings, gases can be separated from air through processes like fractional distillation.

    • 8. Which of the following is the best conductor of electricity?









    Correct Answer: A) Sea water
  • Sea water is the best conductor of electricity because it contains dissolved salts that dissociate into ions, facilitating the flow of electricity.
  • Pure distilled water is a poor conductor of electricity because it lacks free ions.
  • Ordinary water contains impurities and minerals that make it a better conductor than distilled water, but it is still less conductive than sea water.
  • Rainwater can also conduct electricity, but its conductivity depends on the impurities it collects while passing through the atmosphere.
  • In electrical systems, conductive liquids like sea water are sometimes used in experiments and industrial processes.
  • Sea water's high conductivity also makes it dangerous to interact with electrical devices near oceans and seas.

    • 9. Balloons are filled with:









    Correct Answer: A) Helium
  • Helium is a noble gas that is lighter than air, making it ideal for filling balloons so that they float.
  • Unlike hydrogen, helium is non-flammable, making it much safer for use in balloons.
  • Helium is also used in other applications such as cryogenics, airships, and as a cooling medium for superconducting magnets.
  • The gas is extracted from natural gas reserves, particularly in countries like the United States and Qatar.
  • Helium is also used in medical applications, such as MRI scanners.
  • Its low reactivity and inert nature make it an ideal gas for a wide range of applications.

    • 10. The charcoal used to decolourise raw sugar is:









    Correct Answer: A) Animal Charcoal
  • Animal charcoal, also known as bone char, is commonly used to decolourise raw sugar during the refining process.
  • It works by adsorbing impurities and colouring agents from the raw sugar solution.
  • Animal charcoal is made by charring animal bones at high temperatures, resulting in a porous material with a large surface area.
  • It is also used in other industrial applications, including water purification and the removal of heavy metals from solutions.
  • Bone char has been used for sugar refining for centuries, and it is still widely used today in certain regions.
  • Other alternatives, like activated charcoal, are also used for decolourisation, but animal charcoal is particularly effective for sugar.
    • Raghu Sir

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