20 Most VSAQ’s of P – Block Elements Group -14 Chapter in Inter 1st Year Chemistry (TS/AP)

2 Marks

VSAQ-1 : Why does BF3 behave as a Lewis acid?

BF3 acts as a Lewis acid because it is an electron-deficient molecule. It readily accepts a pair of electrons from another molecule or ion to achieve a stable octet electron configuration. This electron-pair acceptance behavior qualifies it as a Lewis acid in chemical reactions.

VSAQ-2 : Explain inert pair effect.

The inert pair effect occurs when the “ns” electrons in heavy elements are less reactive and reluctant to form chemical bonds compared to their “np” electrons.

Example: Thallium (Tl) in Group 13 shows this effect by exhibiting a +1 oxidation state instead of +3, as its “6s²” electrons are less involved in reactions.

VSAQ-3 : Give the formula of borazine. What is its common name?

The formula of borazine is B3N3H6, and its common name is “Inorganic benzene” because it shares a similar structural arrangement with benzene.

VSAQ-4 : Give the formulae of (a) Borax (b) Colemanite

  1. Borax: Na2B4O7·10H2O
  2. Colemanite: Ca2B6O11·5H2O

VSAQ-5 : How does Graphite function as a lubricant?

Graphite functions as a lubricant due to its unique two-dimensional layer structure. The layers in graphite are held together by weak van der Waals forces, allowing them to easily slide over one another. This property reduces friction between surfaces and makes graphite an effective lubricant, reducing wear and facilitating smooth movement in various applications.

VSAQ-6 : Graphite is a good conductor. Explain.

Graphite is an excellent conductor of electricity because of its unique carbon atom arrangement. In graphite, each carbon atom undergoes sp2 hybridization, and one of the resulting hybrid orbitals remains unoccupied. This unoccupied orbital contains a free electron, making it mobile and capable of moving through the structure. These free-moving electrons can carry an electric current, contributing to graphite’s excellent conductivity, which is crucial in various electrical and electronic applications.

VSAQ-7 : Why is diamond hard?

Diamond is hard because its carbon atoms form strong sp³ hybridized covalent bonds, creating a three-dimensional lattice. This network of covalent bonds results in its exceptional hardness, making diamond one of the hardest natural substances.

VSAQ-8 : What is a Banana bond?

A Banana Bond is a unique type of chemical bond found in diboranes (B2H6). It’s referred to as a “banana bond” because of its curved or banana-like shape. This bond is classified as a “3-centered 2-electron bond” because it involves three atoms sharing two electrons in a bonding interaction.

VSAQ-9 : What is allotropy? Give the crystalline allotropes of carbon.

Allotropy is when an element exists in different physical forms while retaining similar chemical properties.

Crystalline Allotropes of Carbon: The crystalline allotropes of carbon include:

  1. Diamond: Known for its hardness and brilliant luster, with each carbon atom bonded tetrahedrally to four others in a three-dimensional lattice.
  2. Graphite: Composed of layers of carbon atoms arranged in hexagonal rings, with weak van der Waals forces between layers, allowing them to slide past each other.
  3. Fullerene: Molecular carbon structures like buckyballs (C60) and nanotubes, known for their unique cage-like or tube-like shapes.

VSAQ-10 : Name any two man-made silicates.

Certainly, two significant man-made silicates are:

  1. Glass: Produced by melting silica (sand) with other materials, it forms a transparent, solid material with various uses.
  2. Cement: Composed mainly of calcium silicates, it’s a crucial binding material in construction and building industries.

VSAQ-11 : Give the use of CO2 in photosynthesis.

In photosynthesis, plants utilize CO2 for the formation of carbohydrates and oxygen. This vital process can be summarized by the equation: 6CO2 + 12H2O → C6H12O6 + 6O2 + 6H2O. CO₂ serves as a key ingredient in the production of sugars and oxygen, which are essential for the plant’s growth and energy storage.

VSAQ-12 : C-C bond length in graphite is shorter than C-C bond length in diamond. Explain.

The difference in C-C bond length between graphite and diamond can be explained by their respective hybridization states:

  1. Graphite: In graphite, carbon-carbon (C-C) bonds are formed through sp2-sp2 overlapping, where carbon atoms have a higher s-character. This high s-character leads to stronger overlapping of orbitals, resulting in shorter C-C bond lengths. In graphite, the C-C bond length is approximately 1.42 angstroms.
  2. Diamond: In contrast, diamond’s C-C bonds are formed through sp3-sp3 overlapping, where carbon atoms have a lower s-character. This reduces the extent of orbital overlap, leading to longer C-C bond lengths. In diamond, the C-C bond length is approximately 1.54 angstroms.

VSAQ-13 : Why is CO poisonous?

Carbon monoxide (CO) is poisonous because it forms a more stable complex with hemoglobin in the blood compared to oxygen. This complex, known as carboxyhemoglobin, prevents hemoglobin from effectively binding with and carrying oxygen throughout the body. As a result, vital organs and tissues do not receive enough oxygen, leading to potentially fatal health consequences, including death.

VSAQ-14 : Write the use of ZSM-5.

ZSM-5 is a type of zeolite known for its use in the conversion of alcohols directly into gasoline. This catalytic process is valuable in the production of gasoline from renewable sources, contributing to the development of alternative and sustainable fuels.

VSAQ-15 : What is meant by Dry ice? Give its applications.

Dry ice refers to solid carbon dioxide (CO2) at a temperature of approximately -78.5°C (-109.3°F). Its applications include:

  1. Refrigeration: Dry ice is used as a refrigerant for preserving and transporting temperature-sensitive items, such as ice cream, frozen food, and medical samples.
  2. Special Effects: It’s used in the entertainment industry to create fog and special effects in theater productions and concerts.
  3. Cleaning: Dry ice blasting is a non-abrasive method used for cleaning surfaces, such as machinery and industrial equipment.
  4. Carbonation: In the beverage industry, it’s employed to carbonate drinks, like sparkling water.

VSAQ-16 : What is ‘producer gas’? How is producer gas prepared?

Producer gas is a mixture of carbon monoxide (CO) and nitrogen gas (N2). It is prepared by passing air over a red-hot carbonaceous fuel, typically coke or coal. The reaction involved in the production of producer gas is:

2C(s) + O2(g) + 4N2(g) → (at around 1273K) 2CO(g) + 4N2(g)

This process results in the formation of carbon monoxide and nitrogen gas, which constitute producer gas. It is used as a fuel in various industrial applications, particularly for heating purposes.

VSAQ-17 : How is water gas prepared?

Water gas is a mixture of carbon monoxide (CO) and hydrogen gas (H2). It is prepared by passing steam (H2O) over red-hot coke (carbon, C). The chemical reaction involved in the production of water gas is:

C(s) + H2O(g) → (at temperatures ranging from 473K to 1273K) CO(g) + H2(g)

This reaction results in the formation of water gas, which is used as a fuel and feedstock in various industrial processes, including the synthesis of chemicals like ammonia and methanol.

VSAQ-18 : What is Synthesis gas?

Synthesis gas, often referred to as “syngas,” is a mixture of carbon monoxide (CO) and hydrogen gas (H2). It is produced by passing steam (H2O) over hot coke (carbon, C). Syngas is a valuable feedstock used in various industrial processes, including the synthesis of methanol and several hydrocarbons. Its versatility makes it a crucial component in the production of a wide range of chemicals and fuels.

VSAQ-19 : Give the hybridisation of carbon in a) CO32- b) diamond c) graphite d) fullerene

Certainly, here are the hybridization states of carbon in the mentioned compounds and materials:

  1. CO₃²⁻ (Carbonate ion): sp2 hybridization.
  2. Diamond: sp3 hybridization.
  3. Graphite: sp2 hybridization.
  4. Fullerene: sp2 hybridization.

VSAQ-20 : What are silicones? Give the uses of silicones.

Silicones are organic-silicon polymers characterized by Si-O-Si linkages.

Uses of Silicones

  1. Silicone Rubber Production: Used in the manufacturing of silicone rubber for various applications, including gaskets, seals, and medical devices.
  2. Waterproofing: Employed to make waterproof clothing, paper, and coatings.
  3. Lubricants: Used as the base for high-temperature and aerospace lubricants and greases.
  4. Paints and Coatings: Included in paints and enamels to enhance their durability and water resistance.