Chemistry Solved SSC-II - Pre-Board Exam - Model Paper - Guess Paper FBISE Class 10

Chemistry SSC-II -  Pre-Board Exam - Model Paper

Guess Paper FBISE Class 10

Ace Your SSC-II Chemistry Exam

 

Solved Pre-Board Model Paper & Guess Paper

Feeling stressed about your upcoming FBISE Class 10 SSC-II Chemistry exam? Don't worry, we've got you covered! This blog post provides a comprehensive breakdown of a solved pre-board model paper and a sample guess paper, including answer explanations for Section A and detailed solutions for selected questions in Section B and C.
By studying these practice papers and understanding the key concepts tested, you'll feel confident and prepared to tackle your exam.

Section-A (Marks-12)                            Time Allowed: 20mins

Pre-Board Exam questions for Chemistry SSC-II, Section-A:

Q1.Circle the correct option A/B/C/D each part carry equal marks

i-The Law of mass action was proposed by

a)Charles b)P. Waage c)M Gulberg d)Both b and c

c) M Gulberg (and) d) Both b and c (P. Waage and M Gulberg)

ii-Which of the following is an lead ore

a)Gelna b)silica c)bauxite d)haematite

- d) haematite (Fe2O3)

iii-which fraction of petroleum is used in chemical feedstock

a)naphtha b)kerosene c)bitumen d)lubricating oil

- a) naphtha (lighter hydrocarbons used for various chemicals)

iv- is used in drips to recover dehydration

a)maltose b)dextrose c)raffinose d)starch

b) dextrose (glucose, a readily absorbed sugar)

v- In which of the following compounds, oxygen is attached to two alkyl carbon

atoms?

a)Alcohol b)Phenol c)Ether d)Ester

c) Ether (R-O-R')

vi- Lewis acid base has following characteristics except

a) formation of adduct

b) formation of coordinate covalent bond

c) donation and acceptance of electron pair

d) donation and acceptance of a proton

d) donation and acceptance of a proton (Brønsted-Lowry theory)

vii- which of the following process is reduction in nature

a)roasting b)smelting c)flotation d)grinding

a) roasting (removal of volatile impurities through heating)

viii-Percentage of sodium chloride in sea water is

a)3.4 b)0.02 c)97 d)2

- a) 3.4% (approximate value)

ix-percentage of nitrogen in urea is

a)75 b)46.4 c)80 d)21

b) 46.4%

x-which is a reddish brown gas

a)chlorine b)nitrogen c)fluorine d)bromine

d) bromine

xi-milk of magnesia Mg(OH)2 is used as antacid it neutralizes excess stomach

acid.which salt is formed in this reaction

a)MgSO4 b)MgO c)MgCO3 d) MgCl2

c) MgCO3 (magnesium carbonate)

xii-for which of the reaction kc has unit mol.dm-3

a)N2+3H2=2NH3

b)PCl5=PCl3+PCl2

c)2ICl=I2+Cl2

d)2NO2=N2O4

a) N2 + 3H2 = 2NH3 (because there are no net changes in the number of moles on either side of the equation)

Pre-Board Exam - Section B

Q2. Answer any eleven questions. Each question carries 3 marks.

i.

Recognizing Equilibrium:

• Constant properties (temperature, pressure, concentration) over time.
• No net change in reactants or products.
• Dynamic process with forward and reverse reactions occurring at equal rates.

OR

• Microscopic Characteristics of Equilibrium:
• Collisions between particles occur at equal rates in both directions.
• Macroscopic properties remain constant due to the cancelling out of microscopic changes.

ii. Given CH3COOH concentration (1 M) and H+ concentration (4.2 x 10^-3 M), vinegar is acidic.

OR

• Equation for water self-ionization: H2O <=> H+ + OH-

iii. Major Commercial Sources of Alkanes:

• Petroleum (crude oil) distillation
• Natural gas

OR

• Functional Group: A specific arrangement of atoms in a molecule that determines its chemical behavior.

iv. Structural Formulas (2-carbon compounds):

• a) Alkyne: CH≡CH (ethyne)
• b) Alcohol: CH3CH2OH (ethanol)
• c) Aldehyde: CH3CHO (ethanal)

v. Propanol Reaction

• Propanol + conc. H2SO4 --> Propene (A) + H2O (Dehydration)
• Propene + Br2 --> 1,2-Dibromopropane (B) (Addition)

OR

• Chlorine reacting with ethane: Cl2 + CH3CH3 --> Multiple products (substitution)
  • CH3CH2Cl (chloroethane)
  • CH2ClCH3 (dichloroethane)
  • CHCl2CH3 (trichloroethane)
  • CCl4 (tetrachloroethane)

vi. Amino Acid Formula: H2N-CHR-COOH (R = side chain)

• Functional Groups: Amino (-NH2), Carboxylic acid (-COOH)

vii. Vitamins: Essential organic compounds required in small amounts for various bodily functions.

• Types of Vitamins:
  • Fat-soluble (A, D, E, K)
  • Water-soluble (B complex, C)

viii. Method for Preparing Alkynes: Elimination reaction from a vicinal dihalide (halogens on adjacent carbons) with a strong base.

ix. Sewage Water Treatment Steps:

1. Screening: Removal of large debris.
2. Primary Clarification: Settling of organic solids.
3. Secondary Treatment: Biological degradation by microorganisms.
4. Disinfection: Killing of harmful bacteria.

OR

• Coagulation in Raw Water Treatment:

• Equation (example): Al2(SO4)3 + 3Ca(HCO3)2 --> 2Al(OH)3 + 3CaSO4 + 6CO2

• Coagulation: Destabilizing colloids in water using a coagulant (e.g., alum) to form larger flocs for removal by settling or filtration.

x. Comparison of Troposphere and Stratosphere

Feature	Troposphere	Stratosphere
Location	Lowest layer	Above troposphere
Temperature	Decreases with altitude	Increases with altitude (due to ozone)
Weather	Most weather phenomena occur	Stable, calm
Water Vapor	Present	Very low
Ozone	Low concentration	Ozone layer (protects from UV)
Height	Up to 18 km (equator), 8 km (poles)	Up to 50 km

xi. Advantages of Solvay Process

• Environmentally friendly (avoids waste products like calcium chloride)
• Produces high-quality sodium carbonate
• Relatively inexpensive

Section C (Attempt any two questions)

These require more detailed explanations. Choose the two you're most comfortable with from the following:

Section C (Chosen Questions)

Q3

a) Water as Proton Donor and Acceptor: Water can function as both a proton donor (acid) and a proton acceptor (base) due to its unique structure.

• Proton Donor: The polar covalent bond between oxygen and hydrogen allows the relatively acidic hydrogen to dissociate as H+, leaving behind OH- (hydroxide ion).

  Equation: H2O <=> H+ + OH-

• Proton Acceptor: The lone pairs of electrons on the oxygen atom can accept a proton (H+) from another molecule, forming H3O+ (hydronium ion).

  Example: NH3 (ammonia) + H2O <=> NH4+ (ammonium ion) + OH-

b) Reaction of KMnO4 with Alkynes: Potassium permanganate (KMnO4) is a strong oxidizing agent that reacts with alkynes (compounds with a carbon-carbon triple bond) to form ketones or carboxylic acids. The specific product depends on the reaction conditions and the structure of the alkyne.

• Overall Reaction:

  2KMnO4 + 5H2C=CH2 + 3H2SO4 --> 2MnSO4 + K2SO4 + 8CO2 + 8H2O

• Reaction Mechanism:

  • KMnO4 is reduced (gains electrons) from the alkyne, breaking the triple bond and forming a diol (double alcohol) intermediate.
  • The diol is further oxidized to a ketone or carboxylic acid depending on the availability of water and the presence of terminal alkynes (triple bond at the end of the carbon chain).

c) Air Pollutants with Sources and Effects:

1. Sulfur Dioxide (SO2):

   • Sources: Coal combustion, industrial processes (smelting)
   • Effects: Respiratory problems (irritation, asthma), acid rain (SO2 reacts with water to form sulfuric acid)

2. Nitrogen Oxides (NOx):

   • Sources: Vehicle emissions, industrial processes (high-temperature combustion)
   • Effects: Smog formation (NOx reacts with sunlight and hydrocarbons), respiratory problems, acid rain (NOx forms nitric acid in the atmosphere)

3. Particulate Matter (PM):

   • Sources: Vehicle emissions, industrial processes (dust, smoke), construction activities
   • Effects: Respiratory problems (irritation, lung disease), cardiovascular issues, visibility reduction

Q4.a)write chemical equations for

i-reaction which occur when temporary hard water is boiled

ii-Ca+2 ions interact with sodium zeolites[6]

b)list some disadvantages of hard water[4]

a) Chemical Equations

i. Temporary Hard Water (Calcium Bicarbonate) Boiling:

Ca(HCO3)2 (aq) --> CaCO3 (s) + CO2 (g) + H2O (l)

Explanation: When temporary hard water containing calcium bicarbonate is boiled, heat decomposes the bicarbonate ion (HCO3^-) into carbon dioxide (CO2) and water (H2O). The calcium cation (Ca2+) combines with the carbonate ion (CO3^2-) to form a solid precipitate of calcium carbonate (CaCO3), which is responsible for scale buildup.

ii. Ca+2 Ions with Sodium Zeolites:

Ca2+ (aq) + 2NaZ (s) --> CaZ2 (s) + 2Na+ (aq)

Explanation: Sodium zeolites (NaZ) are synthetic aluminosilicate minerals with a cage-like structure containing sodium cations (Na+). When hard water containing calcium ions (Ca2+) passes through a zeolite softener, the Ca2+ ions exchange places with the Na+ ions in the zeolite. This process removes the calcium from the water, making it "soft."

b) Disadvantages of Hard Water

1. Scale Buildup: Minerals in hard water can precipitate on surfaces exposed to hot water, forming scale. This can reduce the efficiency of appliances (water heaters) and clog pipes.
2. Soap Scum: Hard water reacts with soap to form insoluble curds (soap scum) that are difficult to rinse off, leaving a filmy residue on skin and surfaces. This reduces the cleaning effectiveness of soap.
3. Textile Damage: Minerals in hard water can attach to fabrics during washing, making them feel stiff and rough.
4. Dishes with Spots: Hard water can leave mineral deposits on washed dishes, leading to a spotted appearance.

Q5.a)Explain solvay process in detail[6]

b)describe acid rain[4]

a) Solvay Process

The Solvay process is a commercial method for producing sodium carbonate (Na2CO3), also known as soda ash. It's a more environmentally friendly alternative to earlier methods that produced calcium chloride (CaCl2) as a waste product.

1. Brine Saturation: Brine (salty water) is saturated with ammonia (NH3) and carbon dioxide (CO2) by bubbling these gases through the solution.

   Equation: 2NH3 (g) + H2O (l) + CO2 (g) <=> (NH4)2CO3 (aq)

2. Ammonium Bicarbonate Formation: The saturated brine reacts with calcium chloride (CaCl2) to form a precipitate of calcium carbonate (CaCO3) and a solution of ammonium bicarbonate ((NH4)2CO3).

   Equation: (NH4)2CO3 (aq) + CaCl2 (aq) --> CaCO3 (s) + 2NH4Cl (aq)

3. Sodium Bicarbonate Precipitation: The ammonium bicarbonate solution is heated, causing it to decompose into sodium bicarbonate (NaHCO3) and ammonium chloride (NH4Cl).

   Equation: (NH4)2CO3 (aq) --> 2NH4Cl (aq) + NaHCO3 (s)

4. Sodium Carbonate Calcination: Sodium bicarbonate is heated in a furnace (calcination) to form sodium carbonate (Na2CO3) and release water (H2O) and carbon dioxide (CO2).

   Equation: 2NaHCO3 (s) --> Na2CO3 (s) + H2O (g) + CO2 (g)

5. Ammonium Chloride Recovery: The ammonium chloride solution from step 3 is used to react with fresh brine, recovering ammonia for reuse in the process.

b) Acid Rain

Acid rain is a form of precipitation (rain, snow, sleet, or fog) that is more acidic than normal. It forms when sulfur dioxide (SO2) and nitrogen oxides (NOx) from vehicle emissions and industrial processes react with water vapor in the atmosphere.

1. Formation of Sulfuric and Nitric Acid:

   • SO2 + H2O --> H2SO3 (sulfurous acid)
   • 2SO2 + O2 --> 2SO3 (sulfuric acid)
   • NOx + H2O --> HNO2 (nitrous acid) and HNO3 (nitric acid)

2. Environmental Effects:

   • Acid rain damages forests and aquatic ecosystems.
   • It accelerates the erosion of buildings and monuments.
   • It can acidify soil and lakes, harming plant and animal life.

3. Control Measures:

• Regulations to reduce emissions of SO2 and NOx from power

Pre-Board Examination Grade 10th Federal  SSC II

Subject: Chemistry Class 10

Exam 2024- Solved - Model Paper

READ MORE

Tips, Test Paper, and Guess Paper for Preparation

FAQs: Pre-Board Examination Grade 10th Federal SSC II - Chemistry Class 10 (Exam 2024)

General:

• What is the purpose of the Pre-Board Examination?

  • The Pre-Board Exam is a practice test designed to help you identify areas you need to focus on before the final SSC II Chemistry exam.

• Is the provided document a real copy of the 2024 exam?

  • No, it's unlikely that the document is the exact copy of the final exam. However, it should be a good representation of the format, difficulty level, and topics covered in the actual exam.

Content:

• What does the "READ MORE" section offer?
  • The "READ MORE" section likely expands on the provided information, offering resources like:
    • Tips on effective exam preparation strategies.
    • Links to practice test papers (different from the solved model paper).
    • Suggestions for creating your own guess paper based on past exams and curriculum guidelines.

Using the Solved Model Paper:

• How can I benefit from the solved model paper?
  • Use the solved model paper to:
    • Familiarize yourself with the exam format (number of sections, question types, time limits).
    • Test your understanding of key chemistry concepts covered in class.
    • Identify areas where you might need extra review or clarification.
    • Practice your test-taking skills, like time management and answering different question types.

Beyond the Model Paper:

• Are there other resources available for exam preparation?
  • Yes! In addition to the provided resources, consider using:
    • Your class notes and textbooks.
    • Past year papers and their solutions (if available).
    • Online resources like educational websites and video tutorials.
    • Study guides or revision booklets for SSC II Chemistry.

Additional Tips:

• Create a study schedule: Plan your study sessions to cover all topics and allocate more time to areas you find challenging.
• Form a study group: Discuss concepts and solve problems together to reinforce your understanding.
• Practice past year papers: This will help you get comfortable with the exam format and improve time management skills.
• Get a good night's sleep: Being well-rested is crucial for performing well on your exam day.

I hope this FAQ helps you effectively utilize the provided resources and ace your Pre-Board Exam and the final SSC II Chemistry exam!