Lahore Board
(2012) Part-I
(Objective type)
Group I
Note: Four possible answers A, B,C and D to each questions are given. The choice which you think is correct, fill that circle in the front of that question with marker or pen ink. Cutting or filling two or more circle will result in zero mark in that question. Write the letter A, B, C or D in the column (Write the correct option) against the each question also. If there is contradiction in the bubble and hand written answer, bubble option will be considered correct.

• The mass of one mole of electrons is:
  
  a) 1.008 mg
  b) 0.55 mg
  c) 0.184
  d) 1.673 mg
  
  
• The number of moles of CO 2 which contain 8.0 g of oxygen is:
  
  a) 0.25
  b) 0.50
  c) 1.0
  d) 1.50
  
  
• The drying agent used in a desiccators is:
  
  a) AgCl
  b) NH₄Cl
  c) CaCl₂
  d) AlCl₃
  
  
• Pressure remaining constant, at which temperature the volume of a gas will become twice of what it is at 0°C:
  
  a) 546°C
  b) 200° C
  c) 546°C
  d) 273° C
  
  
• The partial pressure of oxygen in the lungs is:
  
  a) 760 torr
  b) 670 torr
  c) 159 torr
  d) 116 torr
  
  
• The existence of an element in more than one crystalline form is called:
  
  a) Allotropy
  b) Isotropy
  c) Isomorphism
  d) Polymorphism
  
  
• Acetone and chloroform are soluble in each other due to:
  
  a) Intermolecular hydrogen bonding
  b) Ion- dipole interaction
  c) Instantaneous dipole
  d) Covalent bonding
  
  
• The nature of the positive rays are depends on:
  
  a) The nature of cathode
  b) The nature of Anode
  c) The nature of the residual gas
  d) The nature of the discharge tube
  
  
• Splitting of spectral lines when atoms are subjected to strong electric field is called:
  
  a) Zeeman effect
  b) Stark effect
  c) Compton effect
  d) Photoelectric effect
  
  
• Which of the following molecule has zero dipole moment:
  
  a) NH₃
  b) CHCl₃
  c) H₂O
  d) BF₃
  
  
• The number of bonds in nitrogen molecule is:
  
  a) One sigma and one pi
  b) One sigma and two pi
  c) Three sigma only
  d) Two sigma and one pi
  
  
• If an endothermic reaction allowed to take place very rapidly in the air, the temperature of the surrounding air:
  
  a) Remain constant
  b) in crease
  c)Decrease
  d) Remain unchanged
  
  
• The term pH was introduced by:
  
  a) Henderson
  b) Sorenson
  c) Goldstein
  d) JJ. Thomson
  
  
• Molarity of pure water is:
  
  a) 1
  b) 18
  c) 55.5
  d) 6
  
  
• The oxidation number of chromium in K₂Cr₂O₇ is:
  
  a) 14
  b) 12
  c) 6
  d) 13
  
  
• Reduction always takes place at:
  
  a) Anode
  b) Cathode
  d) Both electrodes
  d) Salt bridge
  
  
• In zero order reaction, the rate is independent of:
  
  a) Temperature of reaction
  b) Concentration of reactants
  c) concentration of products
  d) Concentration of reactants and products

SUBJECTIVE TYPE SECTION – I

2.Write short answers to any eight questions:

• one mg of K₂CrO4 has twice the number of ions than the number of formula units when ionized.
• 4.9 g of H₂SO₄ when completely ionized in water have equal number of positive and negative charges but the number positively charged ions are twice the number of negatively charged ions.
• 23 g of sodium and 39 g of potassium have equal number of atoms in them.
• The desiccators is a safe and reliable method for drying the crystals. explain.
• Media which are used for filtration should be selected on the basis of precipitates. Explain
• Hydrogen and Helium are ideal at room temperature but SO₂ and Cl₂ are non-ideal. explain
• Pressure of NH₃ gas at given condition is less as calculated by Van der waals equation than that calculated by Van der gas equation.
• Water vapours do not behave ideally at 273 K.
•  Some of the postulates of kinetic molecular theory of gases are faulty. justify
• Vacuum distillation can be used to avoid decomposition of a sensitive liquid, explain.
• Heat of sublimation of iodine is very high. justify.Earthenware vessels keep water cool. explain. 

3.Write the short answer of any eight:

•  State pauli-exclusion principle.
• Calculate the mass of an electron when
  e/m =1.758 x 10¹¹ C.kg^-1
• What is Moseley’s law?
• Define Dipole moment? And give its SI unit.
• What is octet rule? Give two examples of compounds which deviate from it.
• Draw labeled diagram of Bomb Calorimeter.
• Define standard enthalpy of formation with a suitable example.
• What are thermo chemical reaction, give their types?
• Aqueous solution of CuSo₄ is acidic in nature. justify it.
• Define “Ebullioscopic Constant ” with one example.
• Give two applications of electrochemical series.
• Define rate of chemical reaction and give its units

4.Write the short answer to any 6 questions:

• Explain why π- bonds are more diffused than σ bonds.
• The melting point, boiling points, heat of vaporizations and heat of sublimations of electrovalent compounds are higher than covalent compounds explain.
• Explain the terms reversible reaction and state of equilibrium.
• The solubility of glucose in water is increased by increasing the temperature, explain.
• Define PH and POH.
• How does the change of pressure shifts the equilibrium position in the synthesis of ammonia?
• Explain how impure Cu can be purified by electrolytic process.
• A salt bridge maintains the electrical neutrality in the cell. explain
• Differentiate between enthalpy change of reaction and energy of activation of reaction.

SECTION –II

Note: Attempt any three questions:

5.(a) What is the difference between actual yield and theoretical yield? Why actual yield is less than theoretical yield?
(b) Classify solids on the basis of bonding. How ionic solids are formed? Give two properties of ionic solids.

6.(a) Write the main postulates of VSEPR theory and explain the structure of ammonia on the basis of this theory.
(b) When 2.00 moles of H₂ and 1.00mole of O₂ at 100°C and 1 torr pressure react to produce 2.00 moles of gaseous water, 484.5 KJ of energy is evolved? What are the values of
(i) ∆H
(ii) ∆E for the production of one mole of H₂O(g)?

7.(a) 250 cm³ of a sample of hydrogen effuses four times as rapidly as 250 cm³ of an unknown gas. Calculate the molar mass of unknown gas.
(b) State and explain with an example, the Hess’s law of constant heat summation.

8.(a) Write a note on synthesis of ammonia gas by Haber’s process keeping in mind the applications of chemical equilibrium in industry.
(b) How can you measure electrode potential of an element with the help of standard Hydrogen Electrode (SHE)?

9.(a) What are ideal solutions? Explain the fractional distillation of ideal mixture of two liquids.
(b) How does Arrhenius equation help us to calculate the energy of activation of a reaction?

Lahore Board
Part-I
(Objective type)
Group II

Note: Four possible answers A, B,C and D to each questions are given. The choice which you think is correct, fill that circle in the front of that question with marker or pen ink. Cutting or filling two or more circle will result in zero mark in that question. Write the letter A, B, C or D in the column (Write the correct option) against the each question also. If there is contradiction in the bubble and hand written answer, bubble option will be considered correct

• Isotopes differ in:

a) Properties which depends upon mass
b) Arrangement of electrons in orbital
c) Chemical properties
d) The extent to which they may be affected in electromagnetic field

• 27g of Al will react completely with how much mass of O₂ to produce Al₂O₃:
  
  a) 8 g of oxygen
  b) 16g of oxygen
  c) 32g of oxygen
  d) 24g of oxygen
  
  
• The comparative rates at which solutes move in paper chromatography depend on:
  
  a) The size of paper
  b) R_f value
  c) Tank
  d) Temperature
  
  
• The molar volume of CO₂ is maximum at:
  
  a) S.T.P
  b) 127°C and 1atm
  c) 0°Cand 2 atm
  d) 273°C and 2 atm
  
  
• A real gas obeying vander waal’s 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
  
  
• London dispersion forces are the only forces present among the:
  
  a) Molecules of water in liquid state
  b) Atoms of helium in gaseous state at high temperature
  c) Molecules of iodine
  d) molecules of hydrogen chloride gas
  
  
• Ionic solids are characterized by:
  
  a) low melting points
  b) good conductivity in solid state
  c) High Vapours pressure
  d) Solubility in polar solvents
  
  
• Orbitals having same energy are called:
  
  a) Hybird Orbitals
  b) Valence Orbitals
  c) Degenerate orbital
  d) d- orbital
  
  
• In the ground state of an atom, the electron is present:
  
  a) In the nucleus
  b) In the second shell
  c) Nearest the nucleus
  d) farthest from nucleus
  
  
• Which of the following molecule, has zero dipole moment:
  
  a) NH₃
  b) CHCl₃
  c) H₂O
  d) Bf₃
  
  
• Bond formed by mutual sharing of electrons is called:
  
  a) Ionic bond
  b) Covalent bond
  c) Co-ordinate covalent bond
  d) All of these
  
  
• For a given process, the heat changes at constant pressure(q_p) and at constant volume (q_v) are related to each other as:
  a) q_p=q_v
  b) q_p<q_v
  c) q_p>q_v
  d) q_p=q_v/2
  
  
• Which statement about the following q=equilibrium is correct:
  2SO₂(g)+O₂(g) (reversible reaction sign) 2SO₃(g) ∆H= -188.3KJ/mol
  
  a)The value_of_K_c falls with a rise in temperature
  b)The value of K_c falls with increasing pressure
  c)Adding V₂O₅ catalyst increase the equilibrium yield of sulphur trioxide
  d)The value of K_p is equal to K_c.
  
  
• Molarity of pure water is:
  
  a) 1
  b) 18
  c) 55.5
  d) 6
  
  
• The potential of standard hydrogen electrode is always fixed as:
  
  a) 1
  b) zero
  c) 1.5
  d) 2
  
  
• The electrode reaction in the electrolysis of dil. H2SO4 with pt electrode is:
  
  a) reduction
  b) Oxidation
  c) Both oxidation and reduction
  d) neither oxidation and reduction
  
  
• The rate of reactions:
  
  a) Increase as the reaction proceeds
  b) Decreases as the reaction proceeds
  c) Remains as the same as the reaction proceeds
  d) May decrease or increase as the reaction proceeds

SUBJECTIVE TYPE
SECTION – I

2- Write short answers to any eight questions:

• What are the molecular ions?
• Define isotopes.
• Differentiate between empirical and molecular formula.
• What do you know about Gooch crucible and sintered glass crucible?
• How crystallized substances are dried?
• Write down the properties of solids.
• Define Avogadro’s law.
• Calculate the no of molecules and no of atoms in 20 cm³ of CH₄ at 0° and 700 mm of mercury pressure.
• Define Joule – Thomson effect.
• Write a brief note on solubility of hydrogen bonded molecules.
• Why evaporation causes cooling?
• Why vapour pressure increase with temperature?

3- Write the short answer of any 8 questions:

• How do you come to know that velocities of electrons in higher orbits are less than in those lower orbits of hydrogen atom?
• Energy of an electron is inversely proportional to ‘n²’ but energies of higher orbits are always greater than those of the lower orbits. justify it.
• Why it is necessary to decrease the pressure in discharge tube to get the cathode rays?
• The distinction between a coordinate covalent bond and a covalent bond vanishes after bond formation in N⁺H₄ and H₃O⁺. Justify it.
• Define ionic bond with an example.
• Is it true that ∆ H and ∆ E have the same values for the reaction taking place in the solution state? Explain.
• What is a thermo-chemical equation? What information does it convey? Explain with an example.
• Define Hess’s law of constant heat summation with one example.
• Relative lowering of vapours pressure is independent of the temperature. justify it.
• Justify that boiling points of the solvents increase due to the presence of solutes.
• What is alkaline battery?
• Differentiate between enthalpy change of reaction and energy of activation of reaction.

4- Write short answer to any 6 questions:

• Why the dipole moment of CO₂ and CS₂ are zero but that of SO_s is 1.61 D?
• pi-bond are more diffused than sigma bonds. Discuss it.
• The change of the temperature disturbs both the equilibrium position and the equilibrium constant of a reaction. Explain it.
• How do the buffer act? Give example.
• What is the effect of catalyst on equilibrium constant?
• How the buffer solutions are prepared?
• The standard oxidation potential of Zn is 0.76 V and its reduction potential is -0.76 V. why?
• Differentiate between electrolytic cell and galvanic cell.
• Explain why the radioactive decay is always a first order reaction.

SECTION II

Note: Attempt any 3 questions:

5.(a) Define limiting reactant. how it is helpful to control the chemical reaction?
(b) Write brief note on :
i- Anisotropy
ii- polymorphism

6.(a) Define Hybridization process and explain the structure of ethyne (C₂H₂) molecule on the bases of it.
(b) If 10.16g of graphite is brunt in a bomb calorimeter and the temperature rise recorded is 3.87K, calculate enthalpy of combustion of graphite? specific heat capacity of calorimeter (bomb, water etc) is 86.02 KJ. mole-¹. k^-1

7.(a) Derive the formula for calculating the energy of an electron in “nth” orbit using Bohr’s Model.
(b) Calculate the density of CH₄(g) at 0°C and 1 atmospheric pressure. what happened to the density if pressure is increased to 2 atmospheres at 0°C?

8.(a) State Le-Chatelier’s principle. Describe the effect of changes in temperature of a system in equilibrium by this principle.
(b) Define: 
         i- Electrode potential
         ii- Redox reaction
         iii- Electrochemical series
         iv- Oxidation number

9.(a) Differentiate between ideal and non ideal solutions.
(b) Write any four characteristics of enzyme catalysis.