The Haryana State Board of Technical Education (HSBTE),  Chemistry for the diploma engineering program of the first-semester examination: February 2023. Here is a sample question paper and answers for the Chemistry Theory examination.

Section A: Multiple Choice Questions (MCQs). Multiple choice questions. All questions are compulsory (6x1=6)

Section B: Objective/Completion type questions. All questions are compulsory. (6x1=6)

Section C: Short answer type questions. Attempt any eight questions out of ten questions. (8x4=32)

Section D: Long answer type questions. Attempt any two questions out of three questions. (2x8=16)

Dr Pramila Singh

Subject: Applied Chemistry, HSBTE, February 2023, Subject Code: 220014, Time : 3 Hrs. M.M.: 60.

SECTION-A

Note: Multiple choice questions. All questions are compulsory (6x1=6)

• Q.1 Which orbital has a dumbbell shape?

• a) s orbital b) p orbital c) d orbital d) f orbital Ans: b) p orbital

Note: The p orbitals have a dumbbell shape. Each p subshell consists of three orbitals, and each orbital has a characteristic dumbbell shape oriented along the x, y, and z axes.

• Q.2 The ability of a metal to be drawn into sheets is known as

• a) ductility b) elasticity c) malleability d) toughness Ans: c) malleability

Note: Malleability is the ability of a material, particularly a metal, to deform under compressive stress, forming a thin sheet or foil without breaking

• Q.3 Which of the following is independent of temperature

• a) molality b) molarity c) normality d) none of the above Ans: a) morality.

Note: Molality (denoted by the symbol "m") is independent of temperature. It is based on the mass of the solvent and the mass of the solute. Molality is defined as the number of moles of solute per kilogram of solvent. In contrast, molarity (option b) and normality (option c) are temperature-dependent concentrations. They involve the volume of the solution

• Q.4 A good fuel should have

• a)high ignition temperature b) moderate ignition temperature

• c) low ignition temperature d) none of the above

• Ans: c) low ignition temperature.

Note: A low ignition temperature means that the fuel can ignite easily, making it more efficient for use

• Q.5 The chemical formula of vinyl chloride is

a) CH CH = CHCI b) CH = CHCI 3 2 c) CH -CH2CI d) Ch = CHCN 3 2

• Ans: b) CH2=CHCl

• Q.6 1 m = ________ nm

• a) 108 b) 109 c) 10-8 d) 10-9 Ans: b) 109109.

SECTION-B

Note: Objective/ Completion type questions. All questions are compulsory. (6x1=6)

• Q.7 Define transition elements.

Ans: Transition elements, also known as transition metals. “Transition elements are found in the d-block of the periodic table. These elements are characterized by the filling of inner d orbitals during the formation of their ions and compounds.” Examples are iron (Fe), copper (Cu), zinc (Zn), chromium (Cr), and nickel (Ni). The properties and behaviors of transition elements are different from those of main group elements.

• Q.8 Define normalizing.

Ans: Normalizing in chemistry is a heat treatment process used to alter the microstructure of materials. This process is commonly associated with steel and other ferrous alloys.

Note: During normalizing, the material is heated to a specific temperature and then allowed to cool in still air. The main objectives of normalizing are to improve mechanical properties, reduce internal stress, and enhance homogeneity. The basic steps involved in the normalizing process are heating, soaking, and cooling.

• Q.9 Define molarity.

Ans: Molarity (often denoted as "M") is the number of moles of solute per liter of solution. The formula for calculating molarity (M) is given by:

• Number of moles of solute/Volume of solution in liters

• Mathematically, it can be expressed as:

• M= n/V

• Where:

• M is the molarity of the solution (in moles per liter),

• n is the number of moles of solute,

Q.10 The amount of heat produced when a unit mass of fuel is burnt is known as_________ Ans: The Heat of Cobution or Calorific value.

Note: Calorific value is expressed in units such as joules per kilogram (J/kg) or kilocalories per kilogram (kcal/kg). It represents the energy released during the complete combustion of one unit mass of a substance, such as a fuel.

There are two main types of calorific values:

1. Higher Calorific Value or Gross calorific value

2. Lower Calorific value or Nert calorific Value

Q.11 An example of solid lubricant is________ Ans:Ans: Graphite

Note: Graphite is a form of carbon that has a layered structure. These layers can slide over each other easily. This property makes graphite an effective solid lubricant. Solid lubricants like graphite are often used in situations where liquid or grease lubricants may not be practical or effective. Graphite is known for its high-temperature stability and resistance to oxidation, making it suitable for applications in high-temperature environments.

Q.12 Define dry corrosion.

SECTION-C

Note: Short answer type questions. Attempt any eight questions out of ten questions. (8x4=32)

Q.13 Write 4 characteristics of ionic compounds.

Ans: Ionic compounds are formed through the transfer of electrons from one atom to another. It results in the formation of ions held together by electrostatic forces.

The following are four characteristics of ionic compounds:

• 1. Ionic Bonding: Ionic compounds are held together by ionic bonds. This is due to the electrostatic attraction between positively charged ions (cations) and negatively charged ions (anions). This bonding occurs when electrons are transferred from one atom to another.

• 2. Crystalline Structure: Ionic compounds typically have a crystalline structure in the solid state. The ions arrange themselves in a three-dimensional pattern known as a crystal lattice..

• 3. High Melting and Boiling Points: Ionic compounds generally have high melting and boiling points compared to molecular compounds. The strong electrostatic forces holding the ions together in the crystal lattice require a more amount of energy to for transition from solid to liquid or gas.

• 4. Conductivity in Molten or Aqueous State: Ionic compounds conduct electricity in their molten state or when dissolved in water (aqueous solution). In the molten state or in solution, the ions are free to move and carry an electric current. However, in the solid state, ionic compounds are typically insulators because the ions are held in a fixed position within the crystal lattice.

Q.14 Define the terms minerals and ore. Write the names of 2 ores of iron.

Ans:

Minerals: A mineral is a naturally occurring inorganic solid with a well-defined chemical composition and a crystalline structure. Examples of minerals are quartz, feldspar, and calcite.

Ore: An ore is a type of rock or mineral deposit that contains a high concentration of valuable minerals or metals. Ores are the source of valuable elements and compounds.

Two Ores of Iron

• 1. Hemalite: It is one of the most abundant and important iron ores. It typically occurs as a red-to-silver-gray metallic mineral. It is the primary ore for iron. It is used in the production of iron and steel

• 2. Magnetite: It is another iron ore that is known for its magnetic properties. It is a black or brownish-black metallic mineral and has high iron content. Magnetite is used in various industrial applications, including the production of iron and steel

Q.15 Define pH. What are the industrial applications of pH? This question was also asked in the HSBTE July 23 Examination.

Ans: Ans: pH is defined as the negative logarithm (base 10) of the hydrogen ion concentration in moles per liter. The pH scale ranges from 0 to 14, where

• · A pH of 7 is considered neutral. It indicates an equal concentration of hydrogen ions and hydroxyl ions

• · A pH less than 7 indicates acidity (higher concentration of hydrogen ions than hydroxyl ions).

• · A pH greater than 7 indicates basicity or alkalinity (higher concentration of hydroxyl ions than hydrogen ions).

The pH of a solution can be calculated using the formula: pH= −log[H+].

Industrial Applications of pH:

• 1. Water Treatment: pH control helps the effectiveness of water treatment chemicals, prevents corrosion of pipes, and ensures the safety of drinking water by maintaining it within a specified pH range.

• 2. Wastewater Treatment: Proper pH conditions are necessary for the effectiveness of biological treatment processes and the precipitation of contaminants.

• 3. Chemical Manufacturing: Many chemical reactions are pH-sensitive. Maintaining the correct pH ensures the desired product is obtained efficiently.

• 4. Food and Beverage Industry: pH affects the taste, texture, and safety of products.

• 5. Textile Industry: Proper pH conditions are necessary to achieve the desired colors. It ensures the quality of the finished textile products.

• 6. Biotechnology and Pharmaceuticals: pH plays an important role in various biotechnological and pharmaceutical processes, such as fermentation, cell culture, and drug formulation.

• 7. Mining and Metallurgy: pH influences the solubility of minerals and helps in the separation of valuable metals from ores.

• 8. Paper and Pulp Industry: pH-controlled paper and pulp production improves the quality of the final product.

• 9. Environmental Monitoring: pH is measured to assess the health of natural water bodies. Changes in pH can indicate pollution or other environmental concerns.

• 10. Electroplating: pH control influences the quality and properties of the plated layers.

Q.16 Define caustic embrittlement. Write 2 disadvantages of caustic embrittlement.

Ans: Caustic embrittlement is a phenomenon that occurs in metals, after their exposure to high-temperature alkaline solutions, such as caustic soda (sodium hydroxide) or caustic potash (potassium hydroxide)

Two disadvantages of caustic embrittlement are:

• 1. Material Weakening: Caustic embrittlement results in a reduction in the mechanical strength and toughness of the affected metal.

• 2. Increased Susceptibility to Cracking: Caustic embrittlement increases the susceptibility of the metal to cracking. Stress corrosion cracking occurs when a material is exposed to both a corrosive environment and mechanical stress.

Q.17 What are the characteristics of a good lubricant? ( 4 only)

Ans: A good lubricant reduces friction, prevents wear, and ensures the smooth operation of machinery. The following are four main characteristics of lubricant:

• 1. Viscosity: The lubricant's resistance to flow is called viscosity. The viscosity affects the lubricant's ability to form a protective film. It maintains a gap between moving surfaces. Low-viscosity lubricants are suitable for high-speed applications. High-viscosity lubricants are better for heavy loads and slow-speed operations.

• 2. Film Strength: The lubricant should have sufficient film strength to prevent metal-to-metal contact between moving surfaces. A strong lubricating film ensures that the lubricant effectively reduces friction and wear.

• 3. Chemical Stability: A good lubricant is chemically stable. Chemical stability ensures that the lubricant maintains its properties and effectiveness.

• 4. Wear Resistance and Extreme Pressure Properties: The lubricant provides effective wear resistance. It protects surfaces and extends the life of components.

Q.18 Briefly explain the fluid film mechanism for lubricants.

Ans: The fluid film lubrication mechanism involves the formation of a thin layer of fluid between two moving surfaces. This layer reduces friction. This mechanism is crucial for the proper functioning and longevity of machinery. The following are brief mechanisms of fluid lubrication.

• 1. Formation of Lubricating Film: A liquid or semisolid lubricant is introduced between the surfaces of moving machinery components. The lubricant forms a thin film when the machinery operates. This thin film separates the two surfaces and prevents direct metal-to-metal contact.

• 2. Hydrodynamic Lubrication: The fluid film operates under the principle of hydrodynamic lubrication. Hydrodynamic lubrication means the relative motion of the surfaces causes the lubricant to flow and generate pressure within the film. The pressure within the lubricating film counteracts the external forces. This creates a lifting effect that keeps the surfaces apart.

• 3. Reduced Friction and Wear: The presence of the fluid film reduces friction between the moving surfaces.

Q.19 Write a short note on metal cladding.

Ans: Metal cladding is a process of layuring one metal over another metal using a bonding process. This process results in the formation of a material that combines the desirable properties of both metals.

Purpose of Metal Cladding: Some common purposes include:

• A. Corrosion Resistance: Cladding with a corrosion-resistant metal helps protect the underlying structure from the environment. It extends the lifespan of a material.

• B. Weather Protection: Cladding acts as a barrier against harsh weather conditions. It prevents moisture, wind, and other environmental factors from affecting the reliability of the structure.

• C. Durability: Cladding adds an extra layer of protection to the structure. It improves the material's resistance to wear and tear, and other forms of damage.

• D. Aesthetic Enhancement: Metal cladding is used to enhance the visual appeal of buildings. It helps to create a unique and attractive cover-up.

• E. Insulation: Some metal cladding systems act as insulation materials. It improves the thermal performance of a building. It increases energy efficiency.

Types of Metal Cladding:

• 1. Sheet Metal Cladding: Thin sheets of metal, such as aluminum, steel, or copper, are applied over the building's exterior.

• 2. Metal Composite Panels: These panels consist of layers of different materials. These layers provide a combination of strength, durability, and aesthetic options.

• 3. Metal Tiles and Shingles: Metal tiles are used for roofing or wall cladding.

• 4. Curtain Wall Systems: Curtain wall systems use metal framing and glass or metal panels to create an external wall. These are commonly used in high-rise buildings for both aesthetic and functional purposes.

Benefits of Metal Cladding:

• 1. Longevity: Metal cladding enhances the lifespan of structures by protecting against corrosion and other environmental factors.

• 2. Low Maintenance: Metal cladding is often low maintenance, requiring minimal maintenance over the years.

• 3. Energy Efficiency: Some metal cladding systems contribute to improved energy efficiency by providing insulation and reflecting sunlight.

• 4. Design Flexibility: Metal cladding offers a wide range of design possibilities. It allows architects and designers to achieve various aesthetic effects

Q.20 Briefly discuss the classification of nanomaterial.

Ans: Nanomaterials have structures or properties that exhibit unique characteristics at the nanoscale,. Their dimensions are less than 100 nanometers. They can be classified based on their dimensions, chemical composition, and the methods used for their synthesis.

A. Based on Dimensions:

• Zero-Dimensional Nano Materials: These are nanoparticles with all three dimensions in the nanoscale. Examples are quantum dots and nanoparticles.

• One-Dimensional Nano Materials: These have one dimension in the nanoscale, such as nanowires, nanotubes, and nanorods.

• Two-Dimensional Nano Materials: Materials with two dimensions in the nanoscale, like graphene and other nanosheets.

B. Based on Chemical Composition:

• Organic Nano Materials: These are nanomaterials composed of carbon-based molecules, such as organic nanoparticles, dendrimers, and carbon nanotubes.

• Inorganic Nano Materials: These are nanomaterials other than carbon, including metal nanoparticles (e.g., gold or silver nanoparticles), metal oxides (e.g., titanium dioxide nanoparticles), and quantum dots.

C. Based on Synthesis Methods:

• Top-Down Approach: Nanomaterials are produced by breaking down larger structures into nanoscale. Examples include mechanical milling and lithography.

• Bottom-Up Approach: Nanomaterials are built up from individual atoms or molecules. Examples include chemical vapor deposition, sol-gel synthesis, and self-assembly techniques.

D. Specialized Classification:

• Polymeric Nano Materials: Nanoscale materials made from polymers, such as nanoparticles or nanocomposites.

• Biological Nano Materials: Nanomaterials with a biological origin or influence, including biomolecules, peptides, and DNA-based nanostructures.

Composite Nano Materials: Materials composed of two or more different types of nanomaterials. They have enhanced or unique properties.

E. Application-Based Classification:

• Nano Electronics: Nanomaterials used in electronic devices, such as quantum dots and nanowires for improved electronic properties.

• Nano Medicine: Nanomaterials designed for medical applications, including drug delivery systems, diagnostic tools, etc.

• Nano Catalysts: Nanomaterials are used as catalysts in various chemical processes.

Q.21 State 4 points of Bohr’s Atomic Model.

Ans: Bohr's Atomic Model, proposed by Niels Bohr in 1913. It helps to understand the structure of atoms. The following are four main points of Bohr's Atomic Model:

• 1. Quantized Energy Levels: Bohr suggested that electrons in an atom occupy orbits. Each orbit corresponds to a specific energy level. Electrons in these orbits do not emit radiation as long as they remain in a stable orbit.

• 2. Angular Momentum Quantization: Bohr proposed that the angular momentum of an electron in a particular orbit is quantized. It is an integer multiple of h/2π (Planck's constant divided by 2π). This quantization of angular momentum stabilizes the electron in its orbit and prevents it from continuously emitting radiation.

• 3. Radiation Absorption and Emission: According to Bohr's model, electrons can absorb or emit energy in packets or quanta when they transition between different energy levels. The energy of these quanta is related to the frequency of the radiation.

• 4. Stability of Certain Orbits: Bohr suggested that electrons revolve in stable orbits without the emission of radiation. These stable orbits correspond to specific energy levels. Electrons in stable orbits do not lose energy and, therefore, do not spiral into the nucleus.

Q.22 State 4 uses of metals.

Ans: Metals are versatile materials. They have a wide range of applications due to their unique physical and chemical properties. The following are four common uses of metals:

• 1. Construction and Building Materials: Metals, such as steel and aluminum are widely used in the construction industry. Steel has high strength and durability. This is commonly used in the construction of buildings, bridges, and infrastructure. Aluminum has low density and corrosion resistance. It is used in lightweight structures, windows, and roofing.

• 2. Transportation: Steel is a primary material for the construction of automobiles, ships, and airplanes due to its strength and durability. Aluminum and titanium are used in the aerospace industry to create lightweight components. This reduces fuel consumption and enhancing performance.

• 3. Electronics and Electrical Devices: Metals like copper and aluminum, are essential in the manufacturing of electrical wiring and components. Copper is an excellent conductor of electricity and is commonly used in electrical wiring. Aluminum is used in power transmission lines due to its lightweight nature.

• 4. Packaging and Containers: Metals, such as aluminum and tinplate, are widely used in the packaging industry. Aluminum is used for beverage cans, food containers, and pharmaceutical packaging due to its lightweight, corrosion-resistant, and recyclable properties. Tinplate, which is steel coated with a thin layer of tin. It is used for packaging food items to prevent corrosion and contamination.

SECTION-D

Note: Long answer type questions. Attempt any two questions out of three questions. (2x8=16)

Q.23 Define the temporary hardness of water. Discuss the Clark method used for the removal of temporary hardness of water.

Ans: Temporary hardness of water is a type of water hardness that can be removed by boiling the water. It is primarily caused by the presence of bicarbonate ions (HCO3-) and carbonate ions (CO3--) in the water. These ions are derived from the dissolution of carbonate minerals in the earth, such as limestone. When water containing these ions is heated, they decompose and release carbon dioxide (CO2). Carbon dioxide forms insoluble carbonate salts, which can be easily precipitated.

Clark's method is one of the techniques used to remove temporary hardness from water. The following are the steps involved in the Clark's method:

• 1. Addition of Calcium Hydroxide (Lime): Calcium hydroxide (Ca(OH)2), also known as lime, is added to the water. The lime reacts with the bicarbonate and carbonate ions present in the water. This reaction forms insoluble calcium carbonate (CaCO3) precipitates.

Ca(OH)2+2HCO3−→CaCO3+2H2O+CO2Ca(OH)2​+2HCO3−​→CaCO3​+2H2​O+CO2​

The calcium carbonate formed is not soluble in water and separates as a solid precipitate.

• 2. Formation of Precipitate: The calcium carbonate precipitate formed during the reaction remains suspended in the water.

• 3. Settling and Filtration:

The water containing the suspended calcium carbonate is allowed to settle at the bottom.

After settling, the clear water is separated from the settled precipitate by filtration. The solid calcium carbonate remains inside the container as a sludge.

The water obtained will be free from temporary hardness.

• 4. Heating (Optional): In some cases, the water may be heated to accelerate the decomposition of any remaining bicarbonate ions. This causes to release of carbon dioxide. This further removes temporary hardness.

Q.24 a) What are the advantages of gaseous fuels over solid and liquid fuels?

Ans: Gaseous fuels, such as natural gas and liquefied petroleum gas (LPG), offer several advantages over solid and liquid fuels in various applications. The following are some advantages of gaseous fuel

• 1. Cleaner Combustion: Gaseous fuels generally produce fewer impurities and pollutants during combustion compared to solid and liquid fuels. These pollutants may be particulate matter, sulfur compounds, etc.

• 2. Higher Energy Efficiency: Gaseous fuels have higher energy content per unit of volume or weight compared to solid and liquid fuels. Thus gaseous fuels have greater energy efficiency in many applications.

• 3. Instantaneous Combustion: Gaseous fuels combust more quickly than solid or liquid fuels. This characteristic allows for more immediate and precise control of the combustion process. This makes them suitable for applications where rapid response and accurate control are essential, such as in heating and cooking.

• 4. Versatility: Gaseous fuels can be used for a wide range of applications, such as heating, cooking, electricity generation, and as a fuel for vehicles. They are suitable for various energy needs.

• 5. Convenient Storage and Transportation: Gaseous fuels are often stored and transported in a compressed or liquefied state. This makes them more convenient to handle than solid or liquid fuels. This ease of storage and transportation contributes to their common use in residential, commercial, and industrial settings.

• 6. Lower Maintenance Requirements: Combustion systems using gaseous fuels require low maintenance compared to systems using solid or liquid fuels. They do not build up deposits in equipment. This leads to longer equipment life and fewer maintenance issues.

• 7. Safety: Gaseous fuels are often considered safer than solid or liquid fuels. For example, in the case of a leak, gaseous fuels are easily detectable due to odorants in the gas.

b) Write a short note on LPG.

Ans: Liquefied Petroleum Gas (LPG) is a flammable hydrocarbon gas that is commonly used as fuel in heating appliances, cooking equipment, and vehicles. It is a byproduct of the petroleum refining process and the extraction of natural gas. It is stored in a liquid state under pressure to facilitate transportation and storage.

The following are features of LPG

• 1. Composition: LPG is primarily composed of propane (C3H8) and butane (C4H10). These hydrocarbons are gaseous at room temperature and atmospheric pressure but can be easily liquefied under moderate pressure.

• 2. Storage and Transportation: LPG is stored and transported in specialized containers under pressure to maintain it in a liquid state. Common storage containers include cylinders, tanks, and bulk storage facilities.

• 3. Uses:

  • Domestic Cooking: LPG is widely used as a clean and efficient fuel for cooking. It provides instant heat and is easy to control.

  • Heating: LPG is used for space heating in homes and businesses. It is also utilized in various industrial processes that require heat.

  • Transportation: LPG is a popular fuel for vehicles. It is more economical than gasoline or diesel. It is commonly used in autogas systems.

• 4. Environmental Impact: LPG is considered a clean-burning fuel compared to traditional fossil fuels. It produces fewer greenhouse gas emissions and air pollutants. It contributes to lower levels of air pollution.

• 5. Safety: LPG requires careful handling due to its flammable nature. Various safety measures, such as odorizing the gas to detect leaks, pressure relief valves, and proper storage practices are a must to ensure its safe use.

• 6. Global Availability: LPG is a globally available energy source. Its demand has been steadily increasing due to its convenience. It is used in both urban and rural areas.

Q.25 Define plastics. State differences between thermoplastic and thermosetting polymers. (6 points)

Ans: Plastics are a group of synthetic materials made from polymers. Polymers are large molecules composed of repeating structural units called monomers. Plastics are known for their malleability, versatility, and ability to be molded into various shapes

There are two types of plastics based on their behavior under heat. These are thermoplastics and thermosetting polymers.

• 1. Thermoplastics: These are polymers that can be melted and re-molded multiple times without undergoing significant chemical degradation. Examples are polyethylene, polypropylene, polyvinyl chloride (PVC), and polystyrene.

• 2. Thermosetting Polymers: These are polymers that undergo a chemical reaction during the molding process. This results in a rigid, infusible structure. Examples are epoxy, phenolic resins, and melamine formaldehyde.

Differences:

• 1. Behavior under Heat:

  • Thermoplastics: They can be melted and re-molded multiple times.

  • Thermosetting Polymers: They undergo a chemical reaction during curing and cannot be re-melted.

• 2. Chemical Structure:

  • Thermoplastics: They have a linear or branched structure.

  • Thermosetting Polymers: They form a three-dimensional network structure during curing.

• 3. Recyclability:

  • Thermoplastics: Generally recyclable.

  • Thermosetting Polymers: Difficult to recycle due to their irreversible curing process.

• 4. Physical Properties:

  • Thermoplastics: Tend to be more flexible and have lower heat resistance.

  • Thermosetting Polymers: Generally exhibit higher heat resistance and dimensional stability.

• 5. Melting Point:

  • Thermoplastics: They have a defined melting point, and they become pliable when heated above this point.

  • Thermosetting Polymers: They do not have a distinct melting point since they undergo a chemical reaction during curing.

• 6. Applications:

  • Thermoplastics: They are widely used where flexibility and the ability to be molded multiple times are essential, such as packaging, toys, and pipes.

• Thermosetting Polymers: They are commonly used ns where durability, heat resistance, and dimensional stability are critical Examples are the production of adhesives, electronic components, etc. is the volume of the solution in liters.

  Dr Pramila Singh