LAHORE BOARD 2017
PAPER CHEMISTRY PART-1
Time: 20 MM. (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.

• The deviation of a gas from ideal behaviour is maximum at:
  
  (A) -10°C and 5.0 atm
  (B) -10 °C and 2.0 atm
  (C) 100°C and 2.0 atm
  (D) 0 °C and 2.0 atm


• Sum of pKa and pKh is equal to:
  
  (A) 7
  (B) 1
  (C) 14
  (D) 0


• In order to mention the boiling point of water at 110 °C, the external pressure should be:
  
  (A) Between 760 torn and 1200 torr
  (B) Between 200 tort and 760 tort
  (C) 765 torr
  (D) Any value of pressure


• The voltage of Nickel Cadmium Cell is:
  
  (A) 1 V
  (B) 1.2 V
  (C) 1.4V
  (D) 1.6 V


• The number of moles of CO; which contain 8.0 g of oxygen:
  
  (A) 0.25
  (0) 0.50
  (C) 1.0
  (D) 1.5


• When 6d orbital is complete, the entering electron goes into:
  
  (A) If
  (B) 7s
  (C) 7p
  (D) 7d


• The rale of reaction:
  
  (A) Increases as the reaction proceeds
  (B) Decreases as the reaction proceeds
  (C) Remains the same as the reaction proceeds
  (D) May decrease or increase us the reaction proceeds


• For which system does the equilibrium constant Kc has units
  
  of (concentration)-1:
  (A) N2+ 3H2=2NH3
  (B) H2+I2=2HI
  (C) 2NO2=N2O4
  (D) 2HF =H2+F2


• The cathodic reaction in the electrolysis of dil. H2S04 with pt electrodes is:
  
  (A) Reduction
  (B) Oxidation
  (C) Both Oxidation and reduction
  (D) Neither oxidation or reduction


• To The volume occupied by 1.4 g of N2 at STP is:
  
  (A) 2.24 dm³
  (B) 22.4 dm³
  (C) 1.12 dm³
  (D) 112 cm³


• Orbitals having same energy are called:
  
  (A) Hybrid orbitals
  (B) Valence orbitals
  (C) Degenerate orbtials
  (D) d-orbitals


• 18 g glucose is dissolved in 90 g of water. The relative lowering of vapour pressure is equal to:
  
  (A) J
  (B) 5.1
  (C) -L
  (D) 6


• Which of the hydrogen halides has the highest percentage of ionic character:
  
  (A) HCI
  (B) HBr
  (C) HF
  (D) HI


• For a given process. the heal changes at constant pressure (qp) and at constant volume (qv) are related to each other as:
  
  (A) qp=qv
  (B) qp<qv
  (C) qp>qv
  (D) qp=


• If absolute temperature of a gas is doubled and the pressure is reduced one half, the volume of a gas will:
  
  (A) Remain unchange
  (B) Increase four times
  (C) Reduce to
  (D) Be doubled


• Diamond is a bad conductor because:
  
  (A) It has a tight structure 
  (B) It has a high density
  (C) There are no free electrons present in the crystal of diamond to conduct electricity.
  (D) In transparent to light


• The comparative rates at which the salutes move in paper chromatography depend upon:
  
  (A) The size of the paper
  (B) values of solutes
  (C) Temperature of the experiment
  (D) Size of the chromatographic tank used  

LAHORE BOARD 2017
PAPER CHEMISTRY PART-1
Time: 3:10 Hours(Subjective Part)
Marks: 83

Section-I

Q.2 Answer any SEVEN parts. All parts carry equal marks.

1. Why 23 g of Na and 238 g of uranium have equal number of atoms in them?
   
2. How Mg - atom is twice heavier than that of C - atom?
   
3. Why 2 g of H₂, 16 g of CH₄ and 44 g of CO₂ occupy separately the volumes of 22.414 dm3 although the sizes and masses of molecules of these three gases are very different from each other?
   
4. Write down the four main characteristics of solvent selected for crystallization of a compound.
   
5. How chemical characterization of a compound is done?
   
6. What do you mean by solvent extraction? Which law controls it?
   
7. Why do we feel comfortable in expressing the densities of gases in units of
   g dm-3 rather than gcm-3,a unit which is used to express the densities of liquids and solids?
   
8. Derive Charles's law by kinetic equation of gases.
   
9. Derive molecular mass of a gas by general gas equation.
   
10. What is Henderson's equation and for which purpose is it used?
    
11. What are applications of buffer in daily life?
    
12. Derive ionic product of water and what is its value at 25 °C?

3. Write short answers to any EIGHT (8) questions.

1. Why ice floats at surface of liquid water?
   
2. Describe cleaning action of soaps and detergents on the basis of H-bonding.
   
3. Why boiling point of water varies from sea-level to higher places?
   
4. Define isomorphism with one example.
   
5. Give products formed due to decay of neutrons.
   
6. Give two postulates of Plank's theory.
   
7. Define Stark's effect.
   
8. Describe  rule for distribution of electrons.
   
9. Give conjugate solution with one example.
   
10. Why NaC and KNO₃ are used to lower melting point of ice?
    
11. Calculate oxidation number of 'S'in H₂SO₄.
    
12. How impure copper can be purified by electrolytic process?

4. Write short answers to any SIX (6) questions.

1. Ionization energy decreases down the group. Why?
   
2. Ionic compounds do not show the phenomena of isomerism. Why?
   
3. Sigma bond is stronger than pi-bond. Why?
   
4. Define ionic and covalent radii.
   
5. Define enthalpy of neutralization and enthalpy of combustion.
   
6. A catalyst is specific in its action. Justify.
   
7. Define homogeneous and heterogeneous catalysis.
   
8. Rate of reaction increases by increasing surface area of reactants. Why?
   
9. What is the effect of temperature on energy of activation of a reaction?

Note: Attempt any THREE question.
SECTION-II
5. (a) Ethylene glycol is used as automobile antifreeze. It has 38.7% carbon, 9.7% hydrogenand 51.6% oxygen. Its molar mass is 62.1 grams mol-1. Determine its empirical and molecular formula.
(b) Elucidate the term ionic solids. Write down three properties of ionic solids.

6. (a) State Graham's law of diffusion. Give its experimental verification.
(b) Derive an expression to calculate the radius of revolving electron in nth orbit by Bohr's model of atom.

7. (a) Describe postulates of valence shell electron pair repulsion theory.
(b) What is Hess's law of constant heat summation? Explain this law with the help of two examples.

8. (a) Explain discharging and recharging in lead accumulator battery.
(b) The solubility product of Ag2CrO4 is 2.6 x10-2 at 25°C. Calculate solubility of compound.

9. (a) Define the following terms: molarity, molality, mole fraction and parts permillion (PPM).
(b) How light and surface area affect the rate of reaction?