SAHIWAL BOARD 2014
PAPER CHEMISTRY PART
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

• Lyman series lies in:
  
  (a) U.V region
  (b) Visible region
  (c) 1.R region
  (d) Microwave region
  
  
• Cathode rays can be generated at the pressure of:
  
  (a) I ton'
  (b) 0.1 torr
  (c) 0.01 torr
  (d) 0.001 torr
  
  
• When water freezes at 0"C, its density decreases due to:
  
  (a) Cubic structure of ice
  (b) Empty spaces among the structure of ice
  (c) Change of bond lengths
  (d) Change of bond angles
  
  
• Shape of Graphite is:
  
  (a) Hexagonal
  (b) Cubic
  (c) Tetragonal
  (d) Monoclinic
  
  
• Plasma is:
  
  (a) First state of matter
  (b) Second state of matter
  (c) Third state of matter
  (d) Fourth state of matter
  
  
• A real gas obeying Vander Waals equation will resemble ideal gas if:
  
  (a) Both "a" and "b" are large
  (b) Both "a" and "b" are small
  (c) "a" is small and "b" is large
  (d) "a" is large and "b" is small
  
  
• Solvent extraction is an equilibrium process and it is controlled by:
  
  (a) Raoult's law
  (b) Henry's law
  (c) Snell's law
  (d) Distribution law
  
  
• Silica gel can be used as:
  
  (a) Oxidizing agent
  (b) Dehydrating agent
  (c) Hydrating agent
  (d) Reducing agent
  
  
• The number of moles of CO₂ which contain 8 g of oxygen.
  
  (a) 0.25
  (b) 0.50
  (c) 1.0
  (d) 1.50
  
  
• The mass of one mole of electrons is:
  
  (a) 1.008 mg
  (b) 0.55 mg
  (c) 0.184 mg
  (d) 1.673 mg
  
  
• With increase of 10"C temperature the rate of reaction doubles.This increase in rate of reaction is due to:
  
  (a) Decrease in activation energy of reaction.
  (b) Decrease in number of collisions b/w reactant molecules.
  (c) Increase in activation energy of reactants
  (d) Increase in number of effective collisions
  
  
• Oxidation number of "Cr " in K₂CrO₄ is:
  
  (a) +2
  (b) +4
  (c) +6
  (d) +8
  
  
• Elevation of boiling point is:
  
  (a) Additive property
  (b) Constitutive property
  (c) Colligativeproperty
  (d) Substitutive property
  
  
• The pH of 1erno/din-3 of an aqueous solution of H,SO, is:
  
  (a) 3.0
  (b) 2.7
  (c) 2.0
  (d) 1.5
  
  
• For the reaction NuOH +HCL ―>NaCl+H₂Othe change is enthalpy is
  
  (a) Heat of reaction
  (b) Heat of formation
  (c) Heat of neutralization
  (d) Heat of combustion
  
  
• Which of the following has zero dipole moment:
  
  (a) H,
  (b) HI
  (c) HCI
  (d) SO,
  
  
• Shape of SnCI₂ is:
  
  (a) Linear
  (b) Trigonal (angular)
  (c) Trigonal (planar)
  (d) Tetrahedral

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

2. Attempt any EIGHT short questions. (8x2=16)

• Define Avogadro's number. Give its numerical value.
• What is molecular ion? Give two examples.
• Write down the names of water absorber and CO, absorber in combustion analysis experiment.
• Give two methods for drying of the crystallized substance.
• How can rate of filtration be increased?
• State Charles's law and give its equation.
• Give two applications of plasma.
• What are units of van-der Waals constants a and b in S.I system?
• Earthenware vessels keep water cool. Why?
• Vacuum distillation can be used to avoid decomposition of a sensitive liquid. Justify it.
• What is Evaporation? How does it cause cooling?
• Define unit cell with example.

3. Attempt any EIGHT short questions. (8x2=16)

• Write two defects of Bohr's atomic model.
• Why e/m value of cathode rays is just equal to that of electron?
• What is the function of principal quantum number?
• Why the positive rays are also called canal rays?
• Name the factors affecting the ionization energy.
• What is "octet rule"?
• The dipole moment of CO₂ is zero and that of H₂0 is 1.85 Debye. Give reason,
• Pi - bonds are more diffused than sigma -bonds. Give reason.
• Define system and surrounding.
• What is standard enthalpy of atomization? Give one example.
• The solubility of glucose in water is increased by increasing the temperature. Give reason.
• Define pH and p0H.

4. Attempt any SIX short questions. (6x2=I2)

• What is the effect of common ion on solubility? Give an example.
• Aqueous solution of CuSO₄ is acidic in nature. Justify it.
• Differentiate between ideal and non ideal solutions.
• What is parts per Million? How it is calculated?
• Give the reactions involved when a lead accumulator (lead storage battery) is discharged.
• Explain how impure Cu can be purified by electrolytic process?
• Write down the chemistry of electrolysis of aqueous solution of NaCI.
• Write any four characteristics of enzyme catalysis.
• What is pseudo first order reaction? Give an example.

SECTION-II

Attempt any THREE questions. (8x3=24)

Question#5
(a) Explain the terms dipole-dipole and dipole induced dipole forces. 4
(b) How carbon, hydrogen and oxygen are estimated in an organic compound by combustion analysis? 4

Question#6
(a) Write down the four postulates of "VSEPR" theory. 4
(b) What is meant by the term Enthalpy of a system? Derive a expression q_p = ΔH. 4

Question#7
(a) Calculate the mass of 1dm³ of NH₃ gas at 30°C and 1000 mmHg pressure, Considering that NH₃ is behaving ideally. 4
(b) Write a detailed note on X-rays. 4

Question#8
(a) Calculate the oxidation numbers of the elements underlined in the following compounds. 4
(i) HNO₃
(ii) Na₂CO₃
(iii) HPO₃
(iv) K₂ MnO₄
(b) What is the percentage ionization of Acetic acid in a solution in which 0.1 moles of it has been dissolved per dm' of the solution where Ka is 1.85. 4

Question#9
(a) Explain positive and negative deviations of non-ideal solution. 4
(b)How will you determine order of reaction by Half life method. 4

SECTION-IV

Attempt any THREE questions. (5x3=15)
Question#10
(a) The given solution contains a mixture of 6.0 grams of NaOH and Na₂S0₄ dissolved per dm³. Find out the percentage of each component volumetrically. (molecular mass of NaOH = 40. 5
(b) Standardize the given solution of iodine. (molecular mass of iodine = 254). 5
(c) Separate the mixture of three inks by chromatography. 5
(d) Prepare pure sample of benzoic acid by crystallization. 5