RAWALPINDI BOARD 2012
CHEMISTRY PART-I
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.

• 27 g of Al react completely with how much mass of O₂ to produce Al₂O₂.

(a) 8 g of Oxygen
(b) 16 g of Oxygen
(c) 32 g of Oxygen
(d) 24 g of Oxygen

• The largest number of molecules are present in:

(a) 3.6g of H₂O
(a) 5.4g of N₂O₅
(c) 4.8g of C₂H₅OH
(d) 2.8g of CO

• During the process of crystallization, the hot saturated solution is:

(a) Cooled very slowly to get large size crystals.
(b) Cooled at fast rate to get medium sized crystals.
(c) Evaporated to get crystals of the product
(d) Mixed with immiscible liquid to get pure crystals of the product.

• Equal masses of methane and Oxygen are mixed in an empty container at 25°C. The fraction of total pressure exerted by Oxygen is:

(a)  
(b)
(c)
(d)

• Number of molecules in one dm3 of water is close to:

(a)   X 1023
(b) 55.6 X 1023
(c)   X 1023
(d)   X 1023

• NH₃ shows a maximum boilling point among hydries of 5th group elements due to:

(a) enhanced electronegative character of nitrogen.
(b) Pyramidal structure of NH₃
(c) Ion pair of electrons present on nitrogen.
(d) very small size of nitrogen atom.

• The molecules of CO₂ in dry ice from:

(a) covalent crystal
(b) Ionic crystals
(c) Amorphous cyrstals
(d) Molecular crystals

• When 6 d orbital is complete, entering electron goes into------------orbital.

(a) 7d
(b) 7f
(c) 7q
(d) 7s

• Splitting of spectral lines when atoms are subjected to strong electric field is called:

(a) Stark effect
(b) Compton effect
(c) Zeeman effect
(d) Photo electric effect

• Which of the following species has unpaired electrons in antibonding molecular orbitals?

(a) F₂
(b) N₂^-2
(c) O₂⁺²
(d) Br₂

• The number of bonds in nitrogen molecule is:

(a) Three sigma bond
(b) one sigma and 2π 
(c) one sigma and one π 
(d) two σ and one π 

• Calorie is equivalent to:

(a) 4.184 J
(b) 418.4 J
(c) 0.4184 J
(d) 41.84 J

• The pH of 10^-3 mol dm^-3 of an aqueous solution of HC1 is:

(a) 1.5
(b) 2.0
(c) 3.0
(d) 2.7

• 18 g glucose is. dissolved in 90 g of water. The relative lowering of vapour pressure is:

(a) 5.1
(b) 
(c)
(d) 3.0

• If the salt bridge is not used between two half cells, then voltage.

(a) Increases slowly
(b) Decreases slowly
(c) Does not change
(d) Drop to zero

• If a Cu strip is placed in a solution of FeSO4-

(a) no reaction
(b) Fe is deposited
(c) Cu is oxidized
(d) Fe is reduced

• If the rate equation of a reaction 2A+B→ products is rate = K [A]²[B]

(a) 2
(b) 1
(c) 3
(d) Zero

Time: 2:40 Hours
(Subjective Part)
Marks: 68
SECTION-I

2. Write short answer any Eight Parts.

• Actual yield of product is usually less than theoretical yield in a chemical reaction. Why?
  
• Calculate the number of CO₂ molecules in 20.0 grams of it.
  
• Define
  
  • (a) molar volume
    
  • (b) molecular formula
    
• Give two application of plasma.
  
• What do you mean by
  
  • (a) charmatogram
    
  • (b) Filtrate
    
• Convert -40° F temperature to kelvin temperature.
  
• Drive SI - units of vander-wal's constants "a" and "b"
  
• State "Graham's Law of Diffusion".
  
• What is cleavage and cleavage plane.
  
• Write down two applications of hydrogen bonding.
  
• What is filter medium. Name two.
  
• What is Lattice and Lattice energy?

3. Write short answer any Eight Parts.

• The abnormality of bond length and bond strength in HI is less prominent than that of HCl. Explain.
  
• Colligative properties are obeyed when the solute is non-electrolyte and also when the solutions are dilute. Explain.
  
• A porous plate or salt bridge is not required in lead storage cell. Explain why?
• Differentiate between internal energy and enthalpy.
  
• What are X-rays. How they are produced?
  
• What is the importance of Mosley's Law?
  
• Define standard enthalpy of atomization with an example.
  
• What are colligative. properties?
  
• π bonds are more diffused than δ bonds. Explain.
  
• Define catalytic poisoning with example.
  
• Explain "the burning of candle is a spontaneous process".
  
• Compare Orbit and Orbital.

4. Write short answer any Six Parts.

• Why the equlibrium constant value has its units for some of the reversible reactions but has no units for some other reactions?
  
• How does the value of equilibrium constant predict the direction of the reaction?
  
• Why the bond angle H₂O molecule is not 109.5o like that of methane.
  
• Calculate the oxidation number of manganese in KMnO₄.
  
• What is ionization constant of acids?
  
• Describe the silver Oxide battery.
  
• Name two applications of solubility product.
  
• Define dipole moment and give its mathematical form.
  
• What is autocatalyst? Give one example.

SECTION-II

5. (a) Define Stoichiometry. Give its assumptions, Mention any two important laws which help to perform stoichiometric calculations.
(b) What are molecular solids? What types of forces are present in them? Write down their properties.

6. (a) Define Co-ordinate covalent bond. Explain with the help of two examples.
(b) Neutralization of 100cm3 of 0.5M NaOH at 25°C with 100cm3 of 0.5M HCl at 25°C raised the temperature-of reaction mixture to 28.5°C. Fins the enthalpy of Naturalization specific heal of water = 4.2JK^-1 g^-1.

7. (a) How Neutrons were discovered?
(b) 250cm³ of sample of hydrogen effuses four times as rapidly as 250cm³ of an unknown gas. Calculate molar mass of unknown gas.

8. (a) What is an Ionic product of water? How does this value vary with the change in temperature?
(b) What are electrolytic cells? Explain with diagram and give an example of electrolysis of fused salt

9. (a) Give the graphical explanation for the elevation of boiling point of a solution. 
(b) Explain half life method for the measurement of the order of a reaction.