Section I: Short Questions
(Answer any five parts)
- Define reversible reaction. Give an example.
- A reversible reaction is a chemical reaction that can proceed in both forward and backward directions.
- Example:
- Write the name of any two atmospheric gases.
- Oxygen (O₂)
- Nitrogen (N₂)
- How do you know that a reaction has achieved an equilibrium state?
- A reaction reaches equilibrium when the rate of the forward reaction equals the rate of the backward reaction, and the concentrations of reactants and products remain constant over time.
- Define Lewis acid and Lewis base.
- Lewis Acid: A substance that can accept a pair of electrons (e.g., H⁺, AlCl₃).
- Lewis Base: A substance that can donate a pair of electrons (e.g., NH₃, OH⁻).
- Which two types of salts produce SO₂ gas on reacting with acids?
- Sulfites (SO₃²⁻)
- Bisulfites (HSO₃⁻)
- What is the pH of pure water?
- The pH of pure water is 7 at 25°C, which is neutral.
- Complete and balance the chemical equation:
- Balanced Equation:
Section II: Short Questions
(Answer any five parts)
- Define molecular formula and give an example.
- The molecular formula represents the actual number of atoms of each element in a compound.
- Example: Water (H₂O)
- Why are the melting and boiling points of organic compounds low?
- Organic compounds have weak intermolecular forces (such as van der Waals forces), which require less energy to break, resulting in low melting and boiling points.
- What are alkyl radicals? Write their general formula.
- Alkyl radicals are groups of carbon and hydrogen atoms derived from alkanes by removing one hydrogen atom.
- General Formula: CₙH₂ₙ₊₁
- What are carbohydrates? Write their general formula.
- Carbohydrates are organic compounds made up of carbon, hydrogen, and oxygen, primarily serving as energy sources.
- General Formula: (CH₂O)ₙ
- Write the general formula of triglycerides.
- Triglycerides are esters derived from glycerol and three fatty acids. Their general formula is:
- What do you mean by ozone hole?
- The ozone hole is the depletion of the ozone layer in the Earth’s stratosphere, primarily caused by chlorofluorocarbons (CFCs).
- Is SO₂ a primary or secondary air pollutant?
- SO₂ (Sulfur dioxide) is a primary air pollutant because it is directly emitted from sources like volcanic eruptions and burning fossil fuels.
Section III: Short Questions
(Answer any five parts)
- Define permanent hardness and temporary hardness of water.
- Permanent Hardness: Caused by sulfates and chlorides of calcium and magnesium, cannot be removed by boiling.
- Temporary Hardness: Caused by bicarbonates of calcium and magnesium, can be removed by boiling.
- Why is water molecule polar?
- Water is polar because of the electronegativity difference between hydrogen and oxygen, causing an unequal charge distribution.
- What is the difference between slag and matte?
- Slag: A byproduct in metal extraction, mainly composed of metal oxides and impurities.
- Matte: A molten mixture of metal sulfides obtained in smelting.
- Which raw materials are required for the formation of Na₂CO₃?
- Sodium chloride (NaCl)
- Limestone (CaCO₃)
- Ammonia (NH₃)
- Write the chemical formula of copper.
- The chemical formula of copper is Cu.
Section IV: Long Questions
(Attempt any two questions)
- Write names of five acids.
- Hydrochloric acid (HCl)
- Sulfuric acid (H₂SO₄)
- Nitric acid (HNO₃)
- Acetic acid (CH₃COOH)
- Phosphoric acid (H₃PO₄)
- What are carbocyclic (homocyclic) compounds? Describe two types with examples.
- Carbocyclic Compounds: Organic compounds that contain rings made entirely of carbon atoms.
- Types:
- Alicyclic Compounds: Cyclohexane (C₆H₁₂)
- Aromatic Compounds: Benzene (C₆H₆)
- Write the general formula of alkenes. Give two methods for the preparation of alkenes.
- General Formula: CₙH₂ₙ
- Preparation Methods:
- Dehydrohalogenation of Alkyl Halides
- Dehydration of Alcohols
- Write down the sources and uses of proteins.
- Sources: Meat, eggs, dairy, legumes, nuts
- Uses: Body growth, repair of tissues, enzyme production, immune system function
- Write steps of manufacturing of urea with the help of a diagram.
- Steps:
- Ammonia (NH₃) reacts with carbon dioxide (CO₂).
- Formation of ammonium carbamate.
- Dehydration of ammonium carbamate to produce urea (NH₂CONH₂).
- Equation:
- Steps:
- Write four effects of acid rain.
- Damage to aquatic life: Lowers pH of water bodies, harming marine organisms.
- Soil degradation: Reduces soil fertility.
- Building corrosion: Erodes limestone and marble structures.
- Health issues: Causes respiratory diseases like asthma.
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