Metallic lustre is due to from Chemistry JEE Year 2013 Free Solv

Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

41.

excess of PCl5 reacts with concentrated H2SO4 giving

  • chlorosulphuric acid

  • sulphurous acid

  • sulphury chloride

  • thionyl chloride


42.

Which one of the following shows highest magnetic moment?

  • Fe2+

  • Co2+

  • Cr3+

  • Ni2+


43.

The emf of a galvanic cell constituted with the electrode Zn2+|Zn (-0.76V) and Fe2+|Fe (-0.41V) is

  • -0.35V

  • + 1.17V

  • +0.35V

  • -1.17V


44.

Which of the following is not a colligative property?

  • Elevation in boiling point

  • Depression in freezing point

  • Osmotic pressure

  • Lowering of vapour pressure


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45.

3 g of urea is dissolved in 45 g of H2O. The relative lowering in vapour pressure is

  • 0.05

  • 0.04

  • 0.02

  • 0.01


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46.

Metallic lustre is due to

  • high density of metals

  • high polish on the surface of metals

  • reflection of light by mobile electrons

  • chemical inertness of metals


C.

reflection of light by mobile electrons

The lustre of metals is due to the free electrons ( or to be precise very loosly bound electrons).When light strikes the surface of the metal, the energy is absorbed by the electrons which absorb and then emit the absorbed energy or reflect it, this cause metals to have lustre.


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47.

Which of the following aqueous solution will exhibit highest boiling point?

  • 0.01M urea

  • 0.01 M KNO3

  • 0.01M Na2SO4

  • 0.015M C6H12O6


48.

Glucose when reduced with HI and red phosphorus gives

  • n-hexane

  • n-heptane

  • n-pentane

  • n-octane


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49.

Oils are liquids at room temperature since they contain higher percentage of

  • oleates

  • palmitates

  • stearates

  • myristates


50.

The number of disulphide linkages present in insulin are

  • 4

  • 3

  • 2

  • 1


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