19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
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
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
In a solid ‘AB’ having the NaCl structure, ‘A’ atoms occupy the corners and face centres of the cubic unit cell but all the face-centred atoms along one of the axes are removed and ‘B’ atoms occupy octahedral voids, t…
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.
Assertion : Co-ordination number of rock salt is 8. Reason : Limiting radius ratio for rock salt is between 0.414 and 0.732.
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:
Assertion : Unlike Schottky defects, Frenkel defects don’t change the density of solids. Reason : These defects are basically point defects.
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
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
Assertion : In Schottky defects, electrical neutrality is maintained. Reason : Equal number of cation and anion vacancies are present.
Example of unit cell with crystallographic dimensions , 90º, 90º a b c is
Ag crystallises as fcc. If radius of Ag is 144 pm then its density will be (a)₁₀ g cm–3
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)
Edge length of a cube is 400 pm, its body diagonal would be
Assertion : Covalent crystals have a higher melting point. Reason : Covalent bonds are stronger than ionic bonds.
Assertion : Glass is an amorphous solid. Reason : In glass, there is only short range order.
Assertion : The window glass of the old buildings is thick at bottom. Reason : Glass is a supercooled liquid of high viscosity and has the property to flow.
Assertion : Packing in body centered cubic (bcc) structure is more efficient than in cubic closed packed (ccp) structure. Reason : 74% of the total space is occupied by the atoms in fcc structure while only 68% of the…
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 : Crystalline solids are anisotropic. Reason : The constituent particles are very closely packed.
Percentage of free space in cubic close packed structure and in body centred packed structure are respectively
Copper crystallises in fcc lattice with a unit cell edge of 361 pm. The radius of copper atom is
Which type of 'defect' has the presence of cations in the interstitial sites ?
Density of NaCl crystal assuming all sites are occupied = 2.178 × 103 kg m–3