SAHIWAL BOARD 2013
PAPER CHEMISTRY PART-I
Time: 20 Min.
(Objective Part)
Marks: 17
Note: You have four choice for each objective type question as A, B, C and D. The choice which you think is correct; fill that circle in front of that question number. Use marker or pen to fill the circles. Cutting or filling two or more circles will result in zero mark in that question.

Question#1

• The volume occupied by 1.4g of N2, at S.T.P is:
  
  (a) 2.24 dm³
  (b) 22.4 dm³ 
  (c) 1.12 dm ³
  (d) 112 dm³
  
  
• The largest number of molecules are present in:
  
  (a) 3.6 g of H₂O
  (b) 4.8 g of C₂H₅OH
  (c) 2.8 g of CO
  (b) 5.4 g of N₂O₅
  
  
• During the process of crystallization, the hot standard solution.
  
  (a) It cooled very slowly to get large sized crystals
  (b) It cooled at moderate rate to get medium sized crystals
  (c) It evaporated to get the crystals of the product
  (d) It mixed with an immiscible liquid to get the pure crystals of the product
  
  
• If absolute temperature of the gas is doubled and the pressure is reduced to one half, the volume of the gas will:
  
  (a) Remains unchanged
  (b) Increase four times
  (c) Reduced to 1/4
  (d) Be doubled
  
  
• In order to mention the boiling point of water at 110°C the external pressure should be:
  
  (a) Between 760 torr and 1200 torn
  (b) Between 200 torr and 760 torr
  (c) 765 torr
  (d) Any value of pressure
  
  
• Ionic solids are characterized by:
  
  (a) Low melting points
  (b) Good conductivity in solid state
  (c) High vapour pressure
  (d) Solubility in polar solvents
  
  
• When 6d orbital is complete, the entering electron goes into:
  
  (a) 7f
  (b) 7s
  (c) 7 p
  (d) 7d
  
  
• Bohr model of atom is contradicted by:
  
  (a) Planck's quantum theory
  (b) Dual nature of matter
  (c) Heisenberg's uncertainty principle
  (d) All of the above
  
  
• The bond order of N₂ molecule is:
  
  (a) 1
  (b) 2
  (c) 3
  (d) 4
  
  
• The tendency of an atom to attract a, shared pair of electron towards itself is called is:
  
  (a) Ionization Energy
  (b) Electron Affinity
  (c) Electro negativity
  (d) Dipole moment
  
  
• Caloric is equivalent to:
  
  (a) 0.4184 J
  (b) 41.84 J
  (c) 41.184 J
  (d) 418.4 J
  
  
• Which statement about the following equilibrium is correct 2SO_2(g)+O_2(G)↔ 2SO_3(g)H=188.3KHmol.
  
  (a) The value of Kp falls with a rise in temperature
  (b) The value of Kp falls with increasing pressure
  (c) Adding V₂O₅ catalyst increase the equilibrium yield of SO₃
  (d) The value of Kp is equal to Ke
  
  
• The solubility product of AgCI is 2.0 x10^-10mol^-6. The maximum concentration of Ag⁺ ions in the solution is:
  
  (a) 2.0x10-10 mol^-3
  (b) 1.4Ix 10-10 mol^-3
  (c) 1.0x 10-10 mol^-3
  (d) 4.0 x10-20 mol^-3
  
  
• Morality of pure water is:
  
  (a) 1
  (b) 18
  (c) 55.5
  (d) 6
  
  
• If a strip of Cu metal is placed in a solution of FeSO₄.
  
  (a) Cu will be deposited
  (b) Fe is precipitated out
  (c) Cu and Fe both dissolved
  (d) No reaction takes place
  
  
• The Oxidation number of O-atom in OF₂ is:
  
  (a) -2
  (b) +2
  (c) -I
  (d) +1
  
  
• In zero order reaction the rate is independent of:
  
  (a) Temperature of reaction
  (b) Concentration of reactants
  (c) Concentration of products
  (d) None of these

Time: 3:10 Hours
(Subjective Part)
Marks: 83
Section II

2. Attempt any EIGHT short questions. (8 x 2 = 16)

• Calculate the moles of oxygen atoms in 9.0 gm of mg (NO,),
• What is stoichionietry? Give two assumptions.
• What is molecular Ion? How it is formed?
• How the crystals are dried in a desicator?
• Define Distribution law. How it is helpful in solvent extraction?
• Calculate value of R in SI units.
• Give any four uses of plasma.
• Explain the process of respiration obeys Dalton's Law of Partial Pressure.
• Metallic crystals are lustrous in nature why?
• Give two uses of liquid crystal.
• Differentiate between Isomorphism and Polymorphism.
• Define lattice energy. Give example.

3. Attempt any EIGHT short questions. (8 x 2 = 16)

• Why the electron moves faster in an orbit of smaller radius?
• Why the potential energy of an electron is negative in an orbit of atom?
• Why 4s sub shell is filled first and 3d afterward?
• Give the electronic configuration, of an element atomic number 24.
• Why the lone pair of electrons occupies more space over the central atom than bond pair.
• Why molecular orbital theory is superior to that of VESPR and VB theory?
• Why He₂ molecule does not exist under normal conditions?
• Define dipole moment and give it's mathematical expression.
• Define enthalpy of neutralization with an example.
• Differentiate between system and surroundings.
• Why HCI is added before passing H₂S gas in qualitative analysis of 2^nd group basic radicals?
• Define pH with mathematical expression.

4. Attempt any SIX short questions. (6 x 2 = 12)

• How does a catalyst affect a reversible reaction?
• How will you prepare 5% W/V area solution in water?
• What is critical solution temperature? Give one example
• NaCl and KNO₃ are used to lower the melting point of ice. Justify it.
• What are the electro chemical series?
• Describe redox reactions which occur during discharging of lead accumulator battery.
• Calculate the oxidation number of 'Mn' in KMnO₄ and MnO₂.
• Differentiate between average and instantaneous rate of reaction.
• Describe two characteristics of a catalyst.

SECTION III

Attempt any THREE questions. (8 x 3 = 24)
Question#5
(a) Defien Vapour pressure. How it is measured by a Manometric Method
(b) NH3 gas can be prepared by heating together two solids NH₄CI and Ca (OH)₂. If a mixture containing 100g of each solid is heated then
(i) Calculate the number of grams of NH₃ product.
(ii) Calculate the excess amount of reagent left unreated
2NH₄C1(s)+Ca(OH)₂(s)—>CaCl₂(s)+2NH₃(g)+2H₂O(1)
where atomic mass of Ca = 40, Cl = 35.5, N= 14, O = 16

Question#6
(a) Define bond energy and explain with the help of a suitable example the effect of the ionic character on its value.
(b) How the enthalpy of a reaction is measured by glass Calorimeter.

Question#7
(a) Derive the van der Wall's equation for real gases and give the physical significances of van der Waal's constants 'a' and b.
(b) What is a Bohr's atomic model? Derive an expression for radius of hydrogen atom.

Question#8
(a) What is electro chemical series? Give its any three applications.
(b) Benzoic Acid, C₆H₅COOH, is a weak monobasic acid (Ka =6.4x10^-5mol dm^-3). What is the pH of a solution containing 7.2g of sodium benzoate (C₆H₅COONa) in One dm^-3 of benzoie Acid. (Atomic masses Na: 23 C: 12)

Question#9
(a) Define Hydrolysis. Why the aqueous solution of NH₄CI is acidic and that of CH₃COONa is basic?
(b) What is enzyme catalysis? Give an example,’ Also give any four characteristics of enzyme.

Section-III
Attempt any THREE questions. (5x 3 = 15)

Write down standard saluting, chemical equation with mole ratio Indicator with end point.
Write down material required Diagram and procedure for part D and E.
(A) You are provided 3g/250 cm³ of mixture of oxalic acid and sodium oxalate. Find out the % age composition of the mixture. (Molecular mass of Oxalic Acid = 126)
(B) Standardize the given solution of KMnO₄ (Molecular Mass of KMnO₄ = 158)
(C) Determine the % age purity of l₂ solution 10 g of which is dissolved in 500 cm³ of solution. Molecular Mass of iodine = 254)
(D) Separate the mixture of inks by paper chromatography.
(E) Purify the given Rock salt.