Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): A two dimensional arrangement where each sphere is in contact with four of its neighbour and has a 2-D coordination number 4 is square close packing arrangement.
Reason (R): In such arrangement, if centres of the neighbouring spheres are joined, a square is formed.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion: In the crystal lattice, the size of the cation is larger in a tetrahedral hole than in an octahedral hole.
Reason: The cations occupy more space than anions in crystal packing.
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Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): The packing efficiency of simple cubic lattice is 52.4%.
Reason (R): The number of atoms per unit cell is 2.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion: Total number of octahedral voids present in the unit cell of cubic close packing including the one that is present at the body center, is four.
Reason: Besides the body center there is one octahedral void present at the center of each of the six faces of the unit cell and each of which is shared between two adjacent unit cells.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): The packing efficiency is maximum for the fcc structure.
Reason (R): The coordination number is 12 in fcc structure.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion: In any ionic solid (MX) with Schottky defects, the number of positive and negative ions is the same.
Reason: Equal number of cation and anion vacancies are present.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): Density of the crystal decreases in Frenkel defect.
Reason (R): In this defect, one of the ion is missing from lattice position and occupies interstitial site.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion: In close packing of spheres, a tetrahedral void is surrounded by four spheres whereas an octahedral void is surrounded by six spheres.
Reason: A tetrahedral void has a tetrahedral shape whereas an octahedral void has an octahedral shape.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): Schottky defect arises when a non-ionic solid is heated.
Reason (R): It happens because some of the lattice sites are vacant in the crystal.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion: The packing efficiency is maximum for the fcc structure.
Reason: The coordination number is 12 in fcc structures.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion: NaCl crystal is sometimes yellow in colour.
Reason: Na+ in the crystal absorbs electrons from the air and hence gives yellow colour.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion: Anion vacancies in alkali halides are produced by heating the alkali halide crystals with alkali metal vapour.
Reason: Electrons trapped in anion vacancies are referred to as F-centers.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion: Group-13 doped crystals of silicon are called p-type semiconductors.
Reason: Holes (Positive in charge) appear to be responsible for the semiconducting properties.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion: On heating ferromagnetic or ferrimagnetic substances, they become paramagnetic.
Reason: The electrons change their spin on heating.
Directions: In the question, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion: Lead zirconate is a piezoelectric crystal.
Reason: Lead zirconate crystals have no dipole moment.