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 Multiple Choice QuestionsMultiple Choice Questions

41.

Diborane reacts with HCl in the presence of AlCl3 and liberates

  • H2

  • Cl2

  • BCl3

  • Cl2 and BCl3


42.

How many corners of SiO4 units are shared in the formation of three dimensional silicates?

  • 3

  • 2

  • 4

  • 1


43.

What is Z in the following reactions ?

BCl3+ H2 450°CCu-Al X + HCl X methylation Z

  • (CH3)BH2

  • (CH3)4B2H2

  • (CH3)3B2H3

  • (CH3)6B2


44.

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

  • Boron

  • Selenium

  • Arsenic

  • Germanium


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45.

Which one of the following elements reacts with steam?

  • C

  • Ge

  • Si

  • Sn


46.

Pure silicon doped with phosphorus is

  • amorphous

  • p-type semiconductor

  • n-type semiconductor

  • insulator


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47.

Al3+, Fe3+, Zn2+ and Ni2+ ions are present in an acidic solution. Excess of ammonium chloride solution followed by addition of ammonium hydroxide solution. The available precipitate will contain

  • Zn(OH)2 and Ni(OH)2

  • Al(OH)2 and Fe(OH)3

  • Zn(OH)2 and Al(OH)3

  • Ni(OH)2 and Fe(OH)3


B.

Al(OH)2 and Fe(OH)3

The increases concentration of NH4+ ions, furnished by the strong electrolyte, NH4Cl, suppresses the ionisation of the weak electrolyte, NH4OH. So, the concentration of OH- ions becomes so low that the product of M3+ ions and the OH- ions exceed the solubility product of hydroxides of Fe and Al. So, they precipitate out. The values of solubility products of hydroxides of Ni and Zn being very high, not exceeded with low concentration of OH- ions.


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48.

Element showing the phenomenon of allotropy is

  • aluminium

  • tin

  • lead

  • copper


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49.

In which of the following the inert pair effect is most prominent?

  • C

  • Si

  • Ge

  • Pb


50.

The metal that does not give the borax bead test is

  • Chromium

  • nickel

  • lead

  • manganese


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