Are you preparing for the HSBTE examination and looking for question papers with solutions for the subject of Applied Chemistry in the 1st semester? In this blog post, we will provide you with HSBTE examination question papers with solutions for the Applied Chemistry,  HSBTE July-23, Examination.

1st Semester HSBTE July 2023

Subject Name: Applied Chemistry Time Allowed: 3 Hrs. MM: 60

Section –A

Note: Multiple Choice questions. All questions are compulsory. 6x1=6

• Q.1 A p orbital can accommodate

(a) 2 electrons with opposite spin (b) 2 electrons with the same spin

(c) 4 electrons (d) 8 electron

Ans: (a) 2 electrons with opposite spin

• Q.2 The metals which are found in nature in a free state are called

(a) metalloids (b) noble gases (c) minerals (d) native metals

Ans: (d) native metals

Note: The metals that are found in nature in the free state, without being chemically combined with other elements, are called native metals.

• Q.3 Which of the following is expressed in mol/kg

(a) normality    (b) morality    (c) molarity    (d) none of the above

Ans: (b) molality

Q.4 What is the main source of lubricating oils?

(a) coal (b) coal gas (c) water (d) petroleum

Ans: (d) petroleum

• Q.5 The monomer unit of polythene is

(a) CF2=CF2 (b) CH2=CH2 (c) CH2=CHCl (d) CH2=CHCN

Ans: (b) CH2=CH2

• Q.6 Corrosion is an example of

(a) oxidation    (b) reduction    (c) electrolysis   (d) combustion

• Ans: (a) oxidation

Section-B

Note: Objective/Completion type questions. All questions arecompulsory. 6x1=6

• Q.7 Define modern periodic law.

• Ans:

• “The modern periodic law states that the properties of elements are a periodic function of their atomic numbers”. When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties. The modern periodic table is arranged based on the atomic number. The atomic number is the number of protons in an atom's nucleus.

• Q.8 The earthy impurities present in the ore are known as----------------.

• Ans: "gangue."

• Note: Gangue refers to the rocky or impurities that are mixed with the mineral ore.

• Q.9 Define normality.

• Ans: The number of equivalents of solute per liter of solution is called normality (N).

• Note: Normality (N) is a measure of the concentration of a solute in a solution. It is used in acid-base chemistry and redox reactions. Normality is expressed in terms of equivalents rather than moles.

• The formula for calculating normality is given by:

• Normality (N)=Number of equivalents of soluteVolume of solution in liter Normalty (N)=Volume of solution in litersNumber of equivalents of solute​

• Q.10 The full form of LPG is ------------------

• Ans: "Liquefied Petroleum Gas."

• Note: LPG is a flammable hydrocarbon gas used to fuel heating appliances, cooking equipment, and vehicles. It is a mixture of propane and butane, and it is stored under pressure in liquid form.

• Q.11 SI unit of viscosity is ----------------.

• Ans: pascal-second (Pa·s) or kilogram per meter per second (kg/(m·s)).

• Note: The SI (International System of Units) unit of viscosity is the pascal-second (Pa·s) or, equivalently, the kilogram per meter per second (kg/(m·s)). Another common unit for viscosity is the poise (P) in the CGS (centimeter-gram-second) system, where 1 poise is equal to 0.1 Pa·

• Q.12 Define carbon-based nanomaterials.

• Ans: Carbon-based nanomaterials refer to a diverse group of materials that are primarily composed of carbon atoms arranged in nanoscale structures. Examples are Graphite, Carbon Nanotubes, Carbon Dots, Graphite Carbon Nitride (g-C3N4), Diamondoids, etc.

Section –C

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

• Q.13 Write a short note on metallic bond.

• Ans: A metallic bond is a type of chemical bond that holds the atoms within a metal. This bond is responsible for the unique properties of metals, The following are features of metallic bonds

• 1. Electronic Delocalization: In a metallic bond, electrons are not limited to individual atoms. They are free to move throughout the entire metal structure. These electrons are referred to as "delocalized" electrons. The ability of electrons to move freely contributes to the high electrical conductivity of metal.

• 2. Conduction of Electricity: The free movement of electrons in a metallic bond is responsible for the excellent electrical conductivity of metals.

• 3. High Melting and Boiling Point: Metals generally have high melting and boiling points. This is because the metallic bond is strong and requires a significant amount of energy to break.

• 4. Metalic Luster: The characteristic luster or shine of metals is due to the ability of electrons to absorb and re-emit photons of light. This is often referred to as the "free electron theory of metals.

• 5. Electrons-sea Model: The electron-sea model describes metallic bonding. Imagine a lattice of metal cations (positive ions) immersed in a "sea" of mobile electrons. The electrons move easily between the positively charged metal ions. This creates a cohesive bond.

• Q.14 Define alloys. What are the purposes of making alloys?

Ans: “Alloys are homogeneous mixtures or solid solutions composed of two or more elements, at least one of which is a metal”.

• The constituents of alloys can be either elements or compounds. They are typically combined to enhance or modify the properties of the individual components. Alloys can exhibit a wide range of physical and mechanical properties that differ from those of pure elements.

• Purpose of Making Allow

  • . Unique Properties: Certain alloys are formulated to exhibit unique properties not found in individual elements. An example is the shape memory alloys. Shape memory alloys can return to their original shape when subjected to certain temperature changes.

  • Improved Mechanical Properties: Alloys have superior mechanical properties compared to their constituent elements. For example, steel is an alloy of iron and carbon that is stronger and harder than pure iron. Enhanced Corrosion Resistance: Alloys are designed to resist corrosion. For example, the addition of chromium to iron forms stainless steel, which has increased corrosion resistance.

  • Hardening and Toughening: Alloys can be designed to be harder than the individual elements. The addition of certain elements can change the microstructure of the alloy. This leads to improved hardness or toughness.

  • Magnetic Properties: Alloys can be designed to have specific magnetic properties. This makes them useful in applications such as magnetic storage devices.

  • Modification of Electrical Properties: Some alloys have specific electrical properties. For example, brass, an alloy of copper and zinc. Brass has better electrical conductivity than pure zinc.

  • Adjustment of Melting Points: Alloys can have melting points different from those of their components.

  • Thermal Properties: Alloys possess specific thermal conductivity or expansion properties. This is important in applications where thermal expansion needs to be controlled.

  • Economic Consideration: Alloys can be more cost-effective than using pure elements for certain applications.

• Q.15 Define pH. What are the industrial applications of pH?

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 in 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 scale & sludge. Write 2 disadvantages of scale & sludge.

Ans:

• Scale: Scale is the deposition of mineral salts, such as calcium carbonate (CaCO3), calcium sulfate (CaSO4), or other compounds. They are formed on surfaces in contact with water. It occurs in pipes, boilers, heat exchangers, etc. Scale build-up reduces the efficiency of equipment and leads to various operational issues.

• Sludge: Sludge is a semi-solid residue. It is formed in liquids, especially in water treatment processes or industrial wastewater treatment. Sludge contains suspended particles, organic matter, and other impurities that settle down from the liquid.

• Disadvantages of Scale

  • 1. Reduced Heat Transfer Efficiency: Scale deposits on heat exchange surfaces. They act as insulators. This insulation reduces the efficiency of heat transfer. It makes systems less effective in transferring heat energy. The reduced efficiency can lead to increased energy consumption and operational costs.

  • 2. Increased Energy Consumption: The presence of scale in pipes and equipment forces the system to work harder. This increased workload results in higher energy consumption. In the case of boilers, for example, scale formation can lead to increased fuel consumption.

• Disadvantages of Sludge

  • 1. Obstruction and Clogging: Sludge accumulation leads to the obstruction and clogging of pipes, pumps, and other equipment. This obstructs the flow of liquids and reduces the efficiency of systems.

  • 2. Environmental Impact: Sludge poses environmental challenges. Disposal of untreated sludge may lead to water pollution or soil contamination.

• Q.17 What are the characteristics of an ideal fuel?( 4 only)

Ans:

• 1. High Energy Content: An ideal fuel should have high energy content per unit mass or volume. This characteristic ensures that a small amount of fuel can provide a major amount of energy.

• 2. Readily available: Ideally fuel should be easily accessible and available in abundant quantities. This ensures a stable and reliable supply.

• 3. Clean Burning: An ideal fuel should burn cleanly with minimal production of pollutants or harmful emissions. Clean combustion reduces environmental impact, improves air quality, and promotes sustainable and eco-friendly energy practices.

• 4. Safe and Convenient to Handle: The handling, storage, and transportation of fuel should be safe and convenient. Ideal fuels are easy to store, transport, and use without posing safety risks. are preferred for practical applications

• Q.18 Briefly explain the properties and uses of CNG.

Ans:

• Properties

  • 1. Composition: CNG is composed of methane (CH4) with a small percentage of other hydrocarbons. It is a fossil fuel extracted from natural gas reservoirs.

  • 2. Physical State: CNG is in a gaseous state at room temperature and is stored under high pressure (typically around 3,000 to 3,600 pounds per square inch or psi) to increase its energy density.

  • 3. Clean Burning: CNG is considered a cleaner alternative to traditional liquid fuels because it burns more cleanly. Combustion of methane produces fewer pollutants such as carbon monoxide (CO) and particulate matter compared to gasoline or diesel.

  • 4. High Ignition Temperature: CNG has a higher ignition temperature than gasoline. Thus, it is safer in the event of a leak. It is less prone to accidental ignition.

• Uses

  • 1. Temperature Fuel: CNG is used as a fuel for vehicles.

  • 2. Industrial and Commercial Applications: CNG is used in various industrial processes, such as heating and manufacturing. It is also employed as a fuel for forklifts and other material-handling equipment in warehouses.

  • 3. Residential Heating: CNG is used for residential heating purposes. It can be supplied through pipelines to homes for space heating and cooking.

  • 4. Electricity Generation: CNG can be used as a fuel for power generation. Gas-fired power plants utilize natural gas, including CNG, to produce electricity.

• Q.19 Write a short note on cementation.

Ans: Cementation is a process used in metallurgy. It is used to extract metals from their ores by using a metal that is more reactive than the metal being extracted. This method is used for the extraction of metals like copper and tin from their ores. The following are steps in cementation

• 1. Selection of Reactant Metals: In cementation, a more reactive metal is chosen as the extracting agent. This metal is known as the cementing agent. It is capable of displacing the metal to be extracted from its compound.

• 2. Preparation of Solution: The ore of the metal to be extracted is dissolved in a suitable solution. The solution contains ions of the metal in a compound. For example, in copper cementation, copper ions may be present in a solution such copper sulfate.

• 3. Introduction of Cementing Agent: The more reactive metal (cementing agent) is introduced into the solution. As the cementing agent is more reactive, it tends to displace the metal ions from the solution. This leads to the formation of a more stable compound of the cementing agent and the formation of extracted metal.

• 4. Precipitation of Metal: The displaced metal ions combine to form a solid precipitate. This precipitate can be separated from the solution.

• Advantages: Cementation is a relatively simple and cost-effective method for extracting certain metals from their ores. It doesn't involve complex equipment or high temperatures.

• Limitations: Cementation is limited to metals that are less reactive than the cementing agent.

• Q.20 Write 4 applications of nanomaterials.

Ans: Materials with structures and properties at the nanoscale (typically dimensions less than 100 nanometers) are called Nanomaterials, They have a wide range of applications

• 1. Medicines and Healthcare:

  • Drug Delivery Systems: Nanomaterials are used to deliver to specific cells or tissues. This minimizes side effects and enhances therapeutic efficiency

  • Medical Imaging: Nanoparticles are used in advanced imaging techniques for early detection of diseases.

• 2. Electronics and Photonics:

  • Nano Electronics: Nanomaterials like carbon nanotubes etc are used in the development of smaller and more efficient electronic components. They offer improved conductivity, thermal properties, and mechanical strength..

• 3. Energy Storage and Conversion:

  • Batteries and Supercapacitors: Nanomaterials, i enhance the energy storage capacity and charging/discharging rates of batteries and supercapacitors..

  • Solar Cells: Nanomaterials like quantum dots and nanowires are used in solar cells to improve light absorption and increase the efficiency of converting sunlight into electricity.

• 4. Environmental Remediation:

  • Water Purification: Nanomaterials, are used for the removal of pollutants and contaminants from water. They can effectively treat wastewater and remove heavy metals, organic pollutants, and other harmful substances.

• Air Filtration: Nanomaterials like nanofibers and nanoparticles are used in air filtration systems to capture and remove particulate matter and pollutants It improves air quality.

• Q.21 State 4 points of difference between orbit and orbital.

Ans: Orbit and orbital are related to atomic structure. But they refer to different aspects. The difference between orbit and orbital:

• 1. Definition:

  • Orbit: An orbit refers to the well-defined path for an electron around the nucleus of an atom. Orbits are based on the Bohr model of the atom.

  • Orbital: An orbital is a region of space around the nucleus. There is a high probability of finding an electron in an orbital of the atom. Orbitals are described by quantum mechanics and are more complex than the Bohr model's orbits.

• 2. Nature:

  • Orbit: Orbits are specific, fixed paths with a definite radius and energy level as proposed by the Bohr model. Electrons move in these orbits without any uncertainty about their position.

  • Orbital: Orbitals are characterized by a distribution rather than a fixed path. The behavior of electrons is wave functions. Orbitals represent regions where there is a high probability of finding an electron.

• 3. Quantum Numbers:

  • Orbit: Orbits are associated with the principal quantum number (n) in the Bohr model. Quantum number (n) determines the energy level of the orbit.

  • Orbital: Orbitals are described by a set of quantum numbers. These are the principal quantum number (n), azimuthal quantum number (l), magnetic quantum number (m), and spin quantum number (s).

• 4. Number of Electrons:

  • Orbit: In the Bohr model, each orbit is associated with a fixed number of electrons. For example, the first orbit can hold up to 2 electrons; the second orbit can hold up to 8 electrons, and so on.

  • Orbital: Orbitals have different shapes and orientations, and each orbital can hold a maximum of two electrons with opposite spins. The number of orbitals within a given energy level depends on the values of quantum numbers.

• Orbits are part of the older Bohr model and represent fixed paths for electrons. Orbitals are a more sophisticated concept in quantum mechanics. It describes the probability distribution of electrons within a given region around the nucleus.

• Q.22 Define the following terms---- Ductility, Elasticity

Ans:

• Ductility: Ductility is a mechanical property of a material that describes its ability to undergo significant deformation or elongation before breakage occurs. Example: Metals such as copper, gold, and aluminum are known for their high flexibility. A ductile material exhibits plastic deformation. It allows to be drawn into wires or shaped into various forms.

• Elasticity: Elasticity is a property of materials that describes their ability to return to their original shape and size after undergoing deformation. Example: Rubber is an example of a highly elastic material. Rubber molecules can temporarily extend, but rubber returns to its original shape.

Section-D

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

• Q.23 Define the permanent hardness of water. Discuss the ion exchange method used for the removal of permanent hardness of water.

Ans:

• Q.24 Define the following terms--- oiliness, viscosity, viscosity index, flash point

• Ans:

• 1. Oiliness: Oiliness is a property of lubricants and oils. It describes their ability to form a protective film or layer on surfaces, reducing friction between moving parts. Oily substances possess a slippery or greasy texture. They are used in various applications, including lubrication in engines and machinery.

• 2. Viscosity: Viscosity is a measure of a fluid's resistance to flow or deformation. It characterizes the internal friction within the fluid. In simple terms, viscosity indicates how easily a fluid can flow. Fluids with high viscosity flow more slowly than fluids with low viscosity. Example: Honey has higher viscosity than water, as it flows more slowly due to its greater resistance to deformation.

• 3. Viscosity Index: The viscosity index (VI) is a numerical scale that shows how the viscosity of oil changes with temperature. A higher viscosity index indicates that the oil's viscosity is less affected by temperature variations. Significance: Lubricating oils with a high viscosity index are preferred because they provide more consistent viscosity under different temperature conditions.

• 4. Flash Point: The flash point of a substance is the lowest temperature at which it can vaporize to form an ignitable mixture in air. It is a critical safety parameter for flammable liquids. Significance: Substances with lower flash points are more volatile and pose a higher risk of igniting.

• Q.25 Define polymer. State the difference between addition and condensation polymers. (6 points).

• Polymer: A polymer is a large molecule composed of repeating structural units called monomers. These monomers are covalently bonded to form a long chain or network. Examples are plastics, rubber, fibers, and biological macromolecules like DNA and proteins.

Difference between Addition and Condensation Polymers:

• 1. Formation Process:

  • Addition Polymers: They are formed by the repeated addition of monomers without the elimination of any byproducts.

  • Condensation Polymers: They are formed by the elimination of a small molecule (such as water or alcohol) during polymerization. Each monomer contributes to the polymer chain, and a byproduct is released.

• 2. Byproducts:

  • Addition Polymers: No byproducts are produced during the polymerization of addition polymers. The entire monomer is incorporated into the polymer chain.

  • Condensation Polymers: Byproducts, such as water or alcohol, are released during the formation of condensation polymers.

• 3. Reaction Type:

  • Addition Polymers: It involves only addition reactions. Double bonds in the monomers break, and new single bonds form without any other chemical changes.

  • Condensation Polymers: It involves both addition and elimination reactions. The monomers react to form a small molecule (byproduct). Byproduct is eliminated during each step.

• 4. Monomer Structure:

  • Addition Polymers: Monomers for addition polymers usually have unsaturated double bonds, such as ethene for polyethylene or styrene for polystyrene.

  • Condensation Polymers: Monomers for condensation polymers have functional groups that react to form covalent bonds between monomers. This releases a small molecule.

• 5. Polymer Structure:

  • Addition Polymers: They have a more straightforward, regular structure because there is no elimination of byproducts. All monomers are incorporated into the chain.

  • Condensation Polymers: They may have a more complex structure due to the elimination of byproducts. The polymer chain may contain different functional groups.

• 6. Examples:

  • . Addition Polymers: Polyethylene, polypropylene, and polystyrene are examples of addition polymers.

  • Condensation Polymers: Nylon, polyester, and polyurethane are examples of condensation polymers.

• Dr Pramila Singh