12th Class Chemistry Sample Paper

done Chemistry Olympiad Sample Paper-1 Total Questions - 13    [Download]

• question_answer1)
  Chromium (III) chloride,\[CrC{{l}_{3}}.6HO\], dissolves in water to form a complex species. If a solution prepared by dissolving 0.1 mole of chromium (III) chloride in water is treated with excess silver nitrate solution, 0.2 mole of silver chloride is precipitated. The most probable formula of the complex species present in the solution is
  A)
   \[{{[Cr{{({{H}_{2}}O)}_{6}}]}^{3+}}\]        
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  B)
   \[{{[Cr{{({{H}_{2}}O)}_{6}}]}^{2+}}\]
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  C)
   \[{{[Cr{{({{H}_{2}}O)}_{4}}C{{l}_{2}}]}^{+}}\]
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  D)
   \[{{[Cr{{({{H}_{2}}O)}_{3}}Cl]}^{2+}}\]
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• question_answer2)
  The atomic number of vanadium (V), chromium (Cr), manganese (Mn) and iron (Fe) are respectively 23, 24, 25 and 26. Which one of these may be expected to have the highest second ionisation enthalpy?
  A)
   Cr                   
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  B)
   Fe
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  C)
   Mn                  
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  D)
   V
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• question_answer3)
  PbS can be separated from ZnS by electrostatic separation method. The property on which this method is based on, is
  A)
   PbS is a good conductor and ZnS is a poor conductor of electricity
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  B)
   PbS is a bad conductor and ZnS is a good conductor of electricity
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  C)
   Both PbS and ZnS are good conductors
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  D)
   Both PbS and ZnS are bad conductors.
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• question_answer4)
  A certain mass of a substance when dissolved in 100 g of benzene\[\left( {{C}_{6}}{{H}_{6}} \right)\], lowers the freezing point by \[{{1.28}^{o}}C.\]The same mass of solute dissolved in 100 g of water lowers the freezing point by \[{{1.40}^{o}}C.\] If the substance has normal molecular weight in benzene and is completely ionised in water, into how many ions does it dissociate in water? \[[{{K}_{f}}({{H}_{2}}O)=1.86K\,\,kg\,\,mo{{l}^{-1}}and\,\,{{K}_{f}}({{C}_{6}}{{H}_{6}})=5.12kg\,\,mo{{l}^{-1}}]\]
  A)
   1           
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  B)
   2             
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  C)
   3          
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  D)
   4
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• question_answer5)
  One mole of an organic compound consumed 3 moles of \[Hl{{O}_{4}}\] during oxidation to give 2 moles of methanoic acid and 2 moles of methanal respectively. The organic compound is
  A)
   \[C{{H}_{2}}OH{{\left( CHOH \right)}_{3}}C{{H}_{2}}OH\]
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  B)
   \[C{{H}_{2}}OH\left( CHOH \right)C{{H}_{2}}OC{{H}_{3}}\]
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  C)
   \[H{{O}_{2}}C{{(CHOH)}_{2}}C{{O}_{2}}H\]
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  D)
   \[C{{H}_{2}}OH{{\left( CHOH \right)}_{2}}C{{H}_{2}}OH\]
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• question_answer6)
  Which of the following represents physical adsorption?
  A)
   
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  B)
   
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  C)
   
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  D)
   
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• question_answer7)
    The correct increasing order of acidity for the given compounds is (i)                   (ii) (iii)            (iv)
  A)
   (iii)\[<\](i)\[<\](iv)\[<\](ii)
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  B)
   (i)\[<\](iii)\[<\](iv)\[<\](ii)
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  C)
   (iv)\[<\](ii)\[<\](i)\[<\](iii)
  done clear
  D)
   (iii)\[<\](iv)\[<\](ii)\[<\](i)
  done clear
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• question_answer8)
  The increasing order for the values of elm (charge/mass) for electron (e), proton (p), neutron (n) and alpha particle  is
  A)
   \[e\,\,,\,\,p\,\,,\,n\,\,,\alpha \]      
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  B)
   \[n\,\,,\,\,p\,\,,\,e\,\,,\alpha \]     
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  C)
   \[n\,\,,\,\,p\,\,,\,\,\alpha \,\,,e\]     
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  D)
   \[n\,\,,\,\,\alpha \,\,,\,\,p\,\,,e\]
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• question_answer9)
  A compound is soluble in cone. \[{{H}_{2}}S{{O}_{4}}\]. It does not decolourise bromine in \[CC{{l}_{4}}\] but is oxidised by chromic any hydride in aqueous sulphuric acid within two seconds, turning orange solution to blue green, then opaque. The original solution contains
  A)
   A secondary alcohol
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  B)
   An alkene
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  C)
   An ether
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  D)
   A primary alcohol.
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• question_answer10)
  In a cubic packed structure of mixed oxides, the lattice is made up of oxide ions, one fifth of tetrahedral voids are occupied by divalent \[({{X}^{2+}})\]ions. while one half of the octahedral voids are occupied by trivalent ions \[({{Y}^{3+}})\], then the formula of the oxide is
  A)
   \[X{{Y}_{2}}{{O}_{4}}\]       
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  B)
   \[{{X}_{2}}Y{{O}_{4}}\]
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  C)
   \[{{X}_{4}}{{Y}_{5}}{{O}_{10}}\]   
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  D)
   \[{{X}_{5}}{{Y}_{4}}{{O}_{10}}\]
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• question_answer11)

  Consider the following statements:

  The rate law for the acid-catalysed hydrolysis of an ester is given as Rate \[=k[{{H}_{2}}O][ester]=k'[ester]\]

  If the acid concentration is doubled at constant ester concentration,

  1. The second order rate constant, k is doubled.

  2. It is a pseudo first order reaction.

  3. The rate of the reaction is unaffected. Which of the above statements are correct?

  A)
   1 and 2           
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  B)
   2 and 3
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  C)
   1 and 3           
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  D)
   1, 2 and 3
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• question_answer12)
  Oxygen is more electronegative than sulphur. Yet \[{{H}_{2}}S\]is acidic while \[{{H}_{2}}O\] is neutral. This is because
  A)
   Water is a highly associated compound
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  B)
   Molecular mass of \[{{H}_{2}}S\] is more than that of \[{{H}_{2}}O\]
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  C)
   \[{{H}_{2}}S\] is gaseous under ordinary conditions while \[{{H}_{2}}O\] is a liquid
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  D)
   H - S bond is weaker than H -O bond.
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• question_answer13)
  Starting with three different kinds of amino acids, how many different kinds of dipeptide molecules can be made assuming each amino acid can be used more than once in a molecule if desired?
  A)
   3                    
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  B)
   6           
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  C)
   9                    
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  D)
   27
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