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The p-Block Elements

Multiple Choice Questions

91.

C-C bond length is maximum in

diamond
graphite
naphthalene
fullerone

92.

Dry ice is

Solid H₂O
Solid CO₂
Solid N₂O₄
Solid NH₃

93.
When borax is heated strongly, it gives

BaBO₂

B₂O₃

B₃N₃H₆

Na₂B₄O₇

B₂O₃

Borax, when heated strongly, gets converted into a glassy bead, called borax bead, which is a mixture of sodium metaborate and boric anhydride.

Na₂B₄O₇.10H₂O $\overset{∆}{\to}$ Na₂B₄O₇ + 10H₂O

Na₂B₄O₇ $\overset{740 ° C}{\to} \underset{Glassy bead}{\underset{⏟}{\underset{Sodium metaborate}{2 {NaBO}_{2}} + \underset{Boric anhydride}{B_{2} O_{3}}}}$

94.

Sindhur, an oxide of lead, is an example of ............. oxide.

basic
super
mixed
amphoteric

95.

The magnetic nature of boron molecule is same as the magnetic nature of

nitrogen molecule
carbon molecule
unipositive nitrogen molecule
oxide ion

96.

Which of the following is not a true alum?

Na₂SO₄.Al₂(SO₄)₃.24H₂O
MgSO₄.Cr₂(SO₄)₃.24H₂O
K₂SO₄.Cr₂(SO₄)₃.24H₂O
(NH₄)₂SO₄.Fe(SO₄)₃.24H₂O

97.

The densities of graphite and diamond at 298 K are 2.25 and 3.31 g cm^-3 respectively. If the standard free energy difference is 1895 J mol^-1, the pressure at which graphite will be transformed into diamond is