Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

In a reaction, A + B C + D, D, 40% of B has reacted at equilibrium, when 1 mole of A was heated with 1 mole of B in a 10 L closed vessel. The value of Kc is

  • 0.44

  • 0.18

  • 0.22

  • 0.36


12.

If the ionc product of Ni(OH)2 is 1.9× 10-15, the molar solubility of Ni(OH)in 1.0 M NaOH

  • 1.9 × 10-18 M

  • 1.9 × 10-13 M

  • 1.9 × 10-15 M

  • 1.9 × 10-15 M


13.

Which one of the following elements on doping with germanium, make it a p-type semiconductor?

  • Boron

  • Selenium

  • Arsenic

  • Germanium


14.

Which one of the following gives sooty flame on combustion?

  • C2H4

  • CH4

  • C2H6

  • C6H6


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15.

What is Z in the following reaction?

CH3-CH2-CO2NaNaOH/CaO Z

  • propane

  • n-butane

  • ethane

  • ethyne


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16.

What are X and Y in the following reaction?

CF2Cl2 UV X + Y

  • CF2Cl, Cl

  • C2F4, Cl2

  • CFCl2, F

  • CCl2, F2


A.

CF2Cl, Cl

Since, chlorofluorocarbon compounds, i.e , freons (CFCs) are non-reactive, non-inflamable, non-toxic organic molecules, these are widely used in air conditioner, refrigerators, in electronic industry for cleaning computer parts. Due to very long life time (CF2Cl2-12 '139 years, CFCl3-11 77 years), these compounds ultimately react the stratosphere where they get broken down by powerful UV radiations and release chlorine free radical. The chlorine free radicals react with ozone and cause its depletion.

     CF2Cl2 hv C·l + C·F2ClCFCl3 hv C·l + C·F2ClHence, x+ y= C·l + C·F2Cl


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17.

Which one of the following elements reacts with steam?

  • C

  • Ge

  • Si

  • Sn


18.

Temporary hardness of water is removed in Clark's process by adding

  • caustic soda

  • calgon

  • borax

  • lime


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19.

Which one of the following correctly represents the variation of electronegatrvity (EN) with atomic number (Z) of group 13 elements?


20.

Which one of the following is more readily hydrolysed by SN1 mechanism?

  • (C6H5)2C(CH3)Br

  • C6H5CH2Br

  • C6H5CH(CH3)Br

  • (C6H5)2CHBr


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