Assertion : Graphite is an example of tetragonal crystal system.R

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 Multiple Choice QuestionsMultiple Choice Questions

491.

The incorrect statement among the following is

  • C60 is an allotropic form of carbon

  • O3, is an allotropic form of oxygen

  • S8 is only allotropic form of sulphur

  • red phosphorus is more stable in air than white phosphorus.


492.

The Ca2+ and F- are located in CaF2 crystal, respectively at face centred cubic lattice points and in

  • tetrahedral voids

  • half of tetrahedral voids

  • octahedral voids

  • half of octahedral voids


493.

If Z is the number of atoms in the unit cell that represents the closest packing sequence... A B C A B C..., the number of tetrahedral voids in the unit cell is equal to

  • Z

  • 2Z

  • Z/2

  • Z/4


494.

What is the co-ordination number of Cl- in NaCl crystal ?

  • 8

  • 6

  • 4

  • 3


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495.

Assertion : Graphite is an example of tetragonal crystal system.

Reason : For a tetragonal system, a = b  c, α=β= 90°,γ= 120°

  • If both assertion and reason are true but reason is not the correct explanation of the assertion.

  • If both assertion and reason are true but reason is not the correct explanation of the assertion.

  • If assertion is true, but reason is false.

  • Both assertion and reason are false statements.


D.

Both assertion and reason are false statements.

Graphite has a two dimensional sheet structure. Each C-atom is in sp2 hybridised state and is linked to three other carbon atoms in a hexagonal planar structure.
For a tetragonal system, a=bc, α=β=γ=90°
For a hexagonal system, a=bc, α=β=90°=γ=120°.


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496.

Schottky defect defines imperfection in the lattice structure of a :

  • solid

  • gas

  • liquid

  • plasma


497.

An AB2 type structure is found in :

  • NaCl

  • CaF2

  • Al2O3

  • N2O


498.

An element (atomic mass 100 g/mol) having BCC structure has unit cell edge 400 pm. The density of element is (No. of atom in BCC (Z) = 2).

  • 2.144 g/cm3

  • 7.289 g/cm3

  • 5.188 g/cm3

  • 10.376 g/cm3


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499.

The crystal system of a compound with unit cell dimensions a= 0.387 nm, b= 0.387 nm and c = 0.504 nm and α-β-90° and γ- 120° is

  • Cubic

  • Hexagonal

  • Orthorhombic

  • Rhombohedral


500.

A solid AB has NaCl type structure. The radius of A+is 100 pm. What is the radius of B-?

  • 190.47

  • 540.13

  • 525

  • 78.12


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