19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
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 : 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 : Glass is an amorphous solid. Reason : In glass, there is only short range order.
Which type of 'defect' has the presence of cations in the interstitial sites ?
Copper crystallises in fcc lattice with a unit cell edge of 361 pm. The radius of copper atom is
Percentage of free space in cubic close packed structure and in body centred packed structure are respectively
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
Assertion : Crystalline solids are anisotropic. Reason : The constituent particles are very closely packed.
Density of NaCl crystal assuming all sites are occupied = 2.178 × 103 kg m–3
A sample of electrically neutral NaCl crystal is analysed for its density which has some unoccupied sites. Two readings where taken.
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 :
Right option for the number of tetrahedral and octahedral voids in hexagonal primitive unit cell are [NEET 2021]
Which type of defect present in NaCl ? (JIPMER 2019)
The number of tetrahedral and octahedral voids in a CCP array of 100 atoms are respectively (Kerala CEE 2014)
Which of the following does not show electrical conduction in its physical state ? (CBSE AIPMT 2013)
Schottky defect in crystals is observed when (RPMT 2010)
The property of crystalline solid is not (OJEE 2010)
In case of semiconductors, the gap between the valence band and conduction band is …A… Here, A refers to
Insulators are the solids with very low conductivities ranging between …A… Here, A refers to
Types of point defects are
In a Schottky defect,
If we mix pentavalent impurity in a crystal lattice of germanium then what type of semiconductor formation will occur?
…A… and …B… are the examples of intrinsic semiconductors. Here, A and B refer to
The structure of MgO is similar to NaCl. What would be the coordination number of magnesium.
For the structure given below the site marked as S is a