Diamond is hard because from Chemistry The p-Block Elements

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Silicon oil is obtained from the hydrolysis and polymerisation of

  • trimetylchlorosilane and dimethyldichlorosilane

  • trimethylchlorosilane and methyldichlorosilane

  • methyltrichlorosilane and dimethyldichlorosilane

  • triethylchlorosilane and dimethyldichlorosilane


2.

The orange solid on heating gives a colourless gas and a green solid which can be reduced to metal by aluminium powder. The orange and the green solids are, respectively

  • NH4Cr2O7 and Cr2O3

  • Na2Cr2Oand Cr2O3

  • K2Cr2O7 and CrO3

  • (NH4)2CrO4 and CrO3


3.

Which of the following oxides is strongly basic?

  • TI2O

  • B2O3

  • Al2O3

  • Ga2O3


4.

Which of the following oxide is amphoteric?

  • SnO2

  • CaO

  • SiO2

  • CO2


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5.

Match the following.
  List I   List II
(A) Flespar (I) [Ag3SbS3]
(B) Asbestos (II) Al2O3.H2O
(C) Pyrargyrite (III) MgSO4.H2O
(D) Diaspore (IV) KAlSi3O8
    (V) CaMg3(SiO3)4

  • (A)   (B)   (C)   (D)

    IV     V      II      I

  • (A)   (B)   (C)   (D)

    IV      V      I      II

  • (A)   (B)   (C)   (D)

    IV      I     III     II

  • (A)   (B)   (C)   (D)

    II      V     IV      I


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6.

Diamond is hard because

  • all the four valence electrons are bonded to each carbon atoms by covalent bonds

  • it is a giant molecule

  • it is made up of carbon atoms

  • it cannot be burnt


A.

all the four valence electrons are bonded to each carbon atoms by covalent bonds

In diamond each carbon atom is linked to four other carbon atoms by sigma bond. Each σC - C bond is formed by the overlapping of sp3 hybrid orbitals of each carbon atoms. Each carbon atom is present at the centre of a regular tetrahedron. Each carbon atom is surrounded by four other carbon atoms present at the corners of a regular tetrahedron. The octet of each carbon atom is complete. Structure of diamond is a rigid three dimensional network. This explain high density and hardness of diamond. Diamond is chemically inactive due to rigid three dimensional structure.
High energy is required to break the large number of σC - C bonds present in diamond. This explain the high melting point of diamond.

                                           


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7.

The decomposition temperature is maximum for

  • MgCO3

  • CaCO3

  • BaCO3

  • SrCO3


8.

Which one of the following reacts with glass?

  • H2SO4

  • HF

  • HNO3

  • K2Cr2O7


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9.

Monosilane on coming in contact with air bums with a luminous flame producing vortex rings. These rings are of

  • SiO2

  • SiO

  • Si

  • H2SiO3


10.

Carborundum is

  • SiC

  • Al2O3·H2O

  • Al2(SO4)3

  • AlCl3


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