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XII-Chemistry Karachi Board

XII-CHEMISTRY
SECTION "A"
Q.1 (A). State Dobereiner's law and Newland law of octaves and distinguish between Modern Periodic Law and Mendleev's Periodic Law.
OR
Discuss the Long form of the Periodic Table on the basis of electronic configuration.
OR
State the Modern Periodic Law, and explain how it removed the defects of Mendleev's System of classification.
OR
Define Periodicity and describe the merits and demerits of Mendleev's Periodic Table.
Q.1 (B). Draw and give the main characteristics of the isotopes of hydrogen and explain why D2O is heavier than H2O.
OR
What are Binary Compounds of hydrogen? How are they classified? Give preparation and properties of complex hydrides.
OR
Why are Alkai and Alkaline earth metal hydrides are called true hydrides?
OR
What is water gas? Give one method for the separation of hydrogen from water gas.
OR
What is atomic hydrogen? Give its preparation, properties and uses.
OR
Write down the points of similarities and difference of Alkalin metals and Alkaine earth metals.
OR
Differentiate between any TWO of the following
p Block Active Elements and p Block Non-Active Elements
Atomic Hydrogen and Nascent Hydrogen
Isotopes of Hydrogen
OR
Discuss the trends of the following down the group in p-Block Elements.
Atomic Radii
Ionization Potential
Electronegativity
Q.1 (C). Give the method for the extraction of alkali metals with reference to the extraction of Sodium metal. Draw the diagram of the cell used in this extraction. Why are anode and cathode compartments separated in the extraction of Sodium? Give the extraction of Sodium by Down's Process.
OR
How Chlorine is obtained from Nelson's Cell or Castner Kellner's Cell, give the important uses of chlorine and write down the auto-oxidation-reduction of Chlorine.
OR
How Hydrogen Sulphide (H2S) gas prepared in the laboratory. Draw the structure of Hydrogen Sulphide gas and explain the reducing action of H2S gas with the help of chemical equation.
Q.1 (D). How does C.F.T explain full the colour of the complex ions.
OR
What is Plastic Sulphur? Why does it show the behaviour of elasticity.
OR
What are outer transition and inner transition elements and how many series of each of them are present in the Periodic Table?
OR
Describe the following properties of a d-block elements.
Complex Formation
Catalyst Properties
Magnetic Properties
Formation of Interstial Compounds
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Q.2 (A). How Caustic Soda (Sodium Hydroxide) is manufactured by Castner-Kellener's Process or by Down's Process. Give the uses of Caustic Soda in industry and also describe the advantages and disadvantages of the process.
OR
How Oil of vitriol (Sulphuric Acid) is manufactured by contact Process? Give the important uses of Sulphuric Acid.
OR
What is Corrosion? Write its causes. Give the different methods for the prevention of metals from corrosion.
Q.2 (B). Starting from Roasted Pyrite ore of Copper, describe how pure Copper is obtained? How is blister Copper refined?
OR
What is matte? Give the extraction of Copper from matte. Draw the diagram of Besmer Converter.
Q.2 (C). Write the Chemical Formulae of the following.
Plaster of Paris
Hypo
Epsom Salt
Oleum
Borax
Lunar Caustic
Red Lead
Water Glass
Potash Alum
Blue Vitriol
Q.2 (D). What are pigments? Describe lead pigments in detail.
OR
Explain the H2SO4 acts as following
Acid
Oxidising Agents
Dehydrating Agents
Q.3 (A). Name the following compounds according to I.U.P.A.C System.
K3[Fe(CN)6]
[Co(en)3](NO3)3
[Cr(NH3)6]Cl3
K2[Cu(CN)4]
[Zn(OH)4]-2
OR
Draw the geometrical shapes of the following complexes.
[Pt(NH3)2Cl2]-2
[Cr(H2O)6]Cl3
[Co(NH3)4Cl2]-2
Q.3 (B). Give three methods of industrial preparation of hydrogen. Hydrogen is misfit in Group IA of the Periodic Table. Give at least four points of justify the statement.
Q.3 (C). Give Scientific reasons of the following.
Graphite is more stable allotropic form of carbon than diamond.
Hydrogen Sulphide is a gas whereas water is a liquid.
Zn(OH)2 is soluble in excesses of NaOH solution.
Every period starts from ns1 and ends at ns2np6.
Water and ammonia molecule acts as ligands but H+3O and NH+4 ions do not.
Q.3 (D). Give the balance chemical equations and explain.
Action of heat on blue vitriol
Action of heat on KMnO4
Action of heat on gypsum
Q.4 (A). Write Short notes on following.
Bleaching Powder
Silvering of Mirror
Boric Acid
Stainless Steel
Thermite Process
Alums
Lunar Caustic
Tin Plating
Blue Vitriol
Photography
Q.4 (B). What happens when? Give chemical equations.
Aluminium is treated with Sodium hydroxide
Litharge is heated with conc. H2SO4
Carbon monoxide is treated with Chlorine
Action of Aqua Regia on gold.
Action of conc H2SO4 on Sucrose.
Q.4 (C). Complete and balance the following chemical equations.
1. Al + H2SO4(dil) --------->
2. H3BO3 + NaOH --------->
3. Al4C3 + H2O --------->
4. Na2CO3 + SiO2 --------->
5. Mg + HNO3(dil) --------->
Q.4 (D). Fill in the blanks with correct answers.
Graphite conducts electricity due to delocalised __________.
The angle between H - S - H molecule is __________.
The refractive index of diamond is __________.
The outer electronic configuration of halogen family is __________.
The mixture of aluminium powder and aluminium nitrate is known as __________.
Ordinary hydrogen is unique is not having __________.

SECTION "B"
Q.5 (A). Define the following terms.
Catenation
Functional Group
Cracking
Aromaticity
Isomerism
Homologous Series
Functional Group Isomerism
Elimination
Orientation
Q.5 (B). Define Organic Compounds. Explain the types of Organic Compounds and briefly describe the natural sources of organic compounds.
OR
What is meant by refining of Petroleum? Name the different fractions of refining of Petroleum.
OR
Give the mechanism of Chlorination in methane in the presence of Sunlight.
OR
How are white solid and red solid obtained from acetylene? Give chemical equation?
OR
Differentiate between aliphatic and aromatic compounds. Give a simple test to identify them.
OR
How will your prepare a sample of benzene from petroleum.
OR
Draw and discuss the orbital structure of following and give the methods of preparation of each with balanced chemical equation.
Methane
Ethane
Ethene
Ethyne
Q.5 (C). How is benzene is commercially prepared from n-Heptane? Explain the structure of benzene by molecular orbital treatment and also describe the stability of benzene ring.
OR
Give a brief account for orientation in benzene.
OR
Why does benzene give electrophilic substitution reactions? Explain the following reactions with their mechanisms.
Halogenation
Friedel Craft Alkylation
Acylation
Q.5 (D). Starting with toluene, how would you prepare p-nitro benzoic acid and m-nitro benzoic acid?
OR
What are nucleophiles and electrophiles? Explain with examples.
Q.6 (A). What are phenols? How are they classified? Explain why phenols are acidic in nature.
OR
What are Alkyl Halides? Give their classification. Explain why primary alkyl halides react by SN2 reaction while tertiary alkyl halides by SN1 reaction.
OR
How would you prepare Grignard's Reagent from alkyl halids? How is Grinard's Reagent used to prepare the following.
Ethane
Propanone
Acetic Acid
Ethyl Alcohol
Q.6 (B). What is Cannizaro's Reaction? Show it by equation.
OR
What is Elimination Reaction. Write down the mechanism of E1 and E2 reactions.
OR
Define functional group. Give a method of preparation of a primary alcohol and write down the reaction of ethanol with the solution metal.
OR
What is meant by fermentation? How is ethyl alcohol obtained by fermentation and molsas? What do you mean by rectified and methylated spirits?
OR
Give two methods of preparation of carboxylic acid and write the reaction of ethanol with acetic acid.
OR
What are aldehydes and Ketons? Give one reaction with an equation to distinguish them.
Q.6 (C). Differentiate between fats and oil and give a brief account of saponification.
OR
What are Degerents? Why they are better cleaning agents than soaps? Give a brief account of the cleaning action of detergents?
Q.6 (D). Write the structural formulae of the following
1, 2 - dibromo - 2 - methyl - propane
Picric acid
3 - ethyl - 1 - heptyne
triphenyl - bromo - methane
ethane - dioic - acid
2 - methoxy propane
Q.7 (A). Give the I.U.P.A.C names of the following
(CH3) - CH - CO - C(CH3)3
CH3 - CH = CHCH3
CH3 - COOH CH (CH3)3
Q.7 (B). What are Carbohydrates? Describe the importance of Carbohydrates in Biochemistry. Describe the classification of Carbohydrates based on their taste.
Q.7 (C). Write True or False for the following statements
1. The deficiency of vitamin "A" causes Xerophthalmia.
2. The bleeding of teeth and scurvy is due to the deficiency vitamin "B".
3. The deficiency of vitamin "C" causes rickets.
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Q.8 (A). Differentiate between the following
Ether linkage and Glycoside linkage
Reducing Sugar and Non-reducing Sugar
Saturated hydrocarbons and Unsaturated Hydrocarbons
OR
Explain the following
Zwitter Ion
Glycisde Linkage
Peptide Linkage
Peptide Bond
Triglycerides
Conjugated Protein
Aldol Condensation
Q.8 (B). What is Life Chemistry? Describe the importance of protein in life chemistry.
OR
Give the definition of Isomerism? What are the different types of Isomerism?
Q.8 (C). Write notes on the following
Plastics
Glass
Fertilizers
Paints
Amino Acids
Lipids
Enzymes
Vitamins
Q.8 (D). Fill in the blanks with the correct answer
A dipolar charged but an overall electricity neutral ions is called __________.
Animal starch is known as __________.
Bakelite is a polymer of phenol and __________.
Resorcinol is not as alcohol but it is a / an __________.
Vitamin B2 is known as __________.
The carbohydrates containing aldehydic group are called __________.

2 comments:

  1. nice.........it is helpful 4 students.

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