19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
The unit cell of a binary alloy composed of A and B metals, has ccp. Structure with A atoms occupying the corners and B atoms occupying centres of each face of the cube. If during the crystallisation of this alloy, in…
Assertion : Graphite is an example of tetragonal crystal system. Reason : For a tetragonal system, a = b c, α = β = γ = 90º.
In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is
A metallic element has a cubic lattice. Each edge of the unit cell is 2 Å. The density of the metal is 2.5 g cm–3 . The unit cells in 200 g of the metal are
Ag crystallises as fcc. If radius of Ag is 144 pm then its density will be (a)₁₀ g cm–3
Edge length of a cube is 400 pm, its body diagonal would be
Sodium metal crystallizes in a body centred cubic lattice with a unit cell edge of 4.29 Å. The radius of sodium atom is approximately:
Density of NaCl crystal by not considering the unoccupied sites but only the occupied sites = 2.165 × 103 kg m–3. The percentage of unoccupied sites in NaCl crystal is
A compound contains two types of atoms X and Y. It crystallises in a cubic lattice with atoms X at the corners of the unit cell and atoms Y at the body centre. The simplest possible formula of this compound is
Assertion : If three elements A, B and C crystallize in a cubic solid lattice with A atoms at the corners, B atoms at the cube centre and C atoms at the centre of the faces of the cube, then the formula of the compoun…
Number of unit cells in 4 g of X (atomic mass=40). Which crystallises in bcc pattern is (NA=Avogadro number)
Example of unit cell with crystallographic dimensions , 90º, 90º a b c is
Copper crystallises in fcc lattice with a unit cell edge of 361 pm. The radius of copper atom is
Total volume of atoms present in a face centred cubic unit cell of a metal is (r = radius of atom) (a) r (b) r (c) r (d) r
Assertion : Crystalline solids are anisotropic. Reason : The constituent particles are very closely packed.
The density of KBr is 2.75 g cm –3. The length of the unit cell is 654 pm. Atomic mass of K = 39, Br = 80. Then the solid is
Density of NaCl crystal assuming all sites are occupied = 2.178 × 103 kg m–3
Assertion : In caesium chloride structure, Cl⁻ ions are at the corners of a primitive cubic array and Cs⁺ ions fits into big central empty region in each Cl⁻ array. Reason : The radius ratio r Cs r Cl is greater than …
Assertion : Covalent crystals have a higher melting point. Reason : Covalent bonds are stronger than ionic bonds.
Percentage of free space in cubic close packed structure and in body centred packed structure are respectively
Which type of 'defect' has the presence of cations in the interstitial sites ?
Assertion : If density of CsCl (cubic structure) is 3.99 g/cm3, the distance between Cs⁺ and Cl⁻ ions will be 357 pm [atomic mass of Cs = 133]. Reason : CsCl has bcc lattice.
A metal crystallises in a face centred cubic structure. If the edge length of its unit cell is ‘a’, the closest approach between two atoms in metallic crystal will be :
Assertion : Unlike Schottky defects, Frenkel defects don’t change the density of solids. Reason : These defects are basically point defects.
Assertion : In Schottky defects, electrical neutrality is maintained. Reason : Equal number of cation and anion vacancies are present.