CBSE
Multiple Choice QuestionsIn tetragonal crystal system, which of following is not true?
All axial lengths and all axial angles are equal.
All three axial lengths are equal.
All three axial angles are equal.
Two axial angles are equal but the third is different.
Schottky defect in crystals is observed when
unequal number cations and anions are missing from the lattice
equal number of cations and anions are missing from the lattice
an ion leaves its normal site and occupies an interstitial site
density of the crystal is increased.
Assertion: Due to Frenkel defect, density of the crystalline solid decreases.
Reason : In Frenkel defect, cation or anion leaves the crystal.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
The coordination number in hcp is
6
12
18
24
Assertion : bcc and hcp has same packing efficiency.
Reason : Both have same number of atoms per unit cell and same arrangement.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
In face centred cubic unit cell edge length is :
r
r
2r
r
Schottky defect is
vacancy of ions
delocalization of ions
interstitial vacancy of ions
vacancy of only cations
In solid ice, oxygen atom is surrounded
tetrahedrally by 4 hydrogen atoms
octahedrally by 2 oxygen and 4 hydrogen atoms
tetrahedrally by 2 hydrogen and 2 oxygen atoms
octahedrally by 6 hydrogen atoms
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
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.
