InSb, AlP and GaAs are semiconductors made by combining ____.
I, Al and Ga are 13 group elements and Sb,P and As are 15 group of elements. Hence, the combination is a 13 - 15 impurity semiconductor.
The packing efficiency in a square closed pack crystal is____.
The arrangement of scp crystal is A--A---A-- type of arrangement. The void formed is wider compared to BCC or HCP or CCP crystal. Hence, the packing efficiency of FCC (HCP or CCP) = 74%, packing efficiency of BCC = 68% and that of SCP = 52.4%. Hence, packing efficiency in SCP is minimum.
A solid with high electrical and thermal conductivity from the following is
Out of the given substances, only Li has high electrical and thermal conductivity.
Oxides of ____ metal show metallic or insulating property, depending on the temperature.
Certain oxides of vanadium like VO, VO2 , VO3 ,and TiO3 show metallic and insulating property, depending on the temperature.
The limiting radius ratio for tetrahedral shape is:
For tetrahedral shape radius ratio is 0.225 – 0.414.
Which of the following compounds is a good conductor of electricity in solution state?
Ionic compounds are dissociated in solution state and form ions. Ions are good carrier of charge. So it makes solution conducting.
Of the options given ____is a covalent solid.
Silicon Carbide is carborundum (SiC). It is a strong covalently bonded molecule. It forms a strong covalent molecule. Auminium is a metal, which has a metalic bond. Argon molecules are held by weak vander Waals forces and form a Non- polar molecular solid. Calcium flouride forms an ionic solid, with Ca2+ ions and F1- ions arranged in a regular fashion.
In ceasium chloride, which is a body center cube, the number of CsCl molecules per unit cell would be ____.
In Ceasium chloride, chlorine atoms occupy the corners and the ceasium occupies the body center. Hence, the no. of chloride ions per unit cell is 1/8 x 8 = 1. Ceasium, being in the body, contributes one to the unit cell. Hence, one ceasium and one chlorine form one molecule.
Glass is classified as a/ an
Glass is classified as a pseudo solid. Pseudo solid, as the name indicates is not a pure solid. Glass has the fluid character like liquid as well as it is very hard like solids. It is formed by supercooling of liquid SiO2 mixture.
A compound forms a ccp structure. The total number of tetrahedral voids in the crystal of 0.5 mol is____ .
1 mol = 6.023 x 1023 voids, 0.5 mol = 3.011 x 1023 voids (total voids) , Total number of voids = 3 (i.e. 2 tetrahedral voids + 1 octahedral void) Total no. of tetrahedral voids = 2/3 x 3.011 x 1023 = 2.006 x 1023 voids.
CrO2, a ferromagnetic material is used to make ____.
CrO2 is used to make magnetic tapes used for audio recording. It is found in all audio cassettes and video cassettes.
The fraction of vacant space in a BCC structure is____.
The packing efficiency of BCC arrangement is 68%. Thus, the space occupied by the atoms in a BCC structure is 0.68. Then, the fraction of vacant space left out would be 0.32.
The constituent particles of metallic solids are ____.
In metallic solids, the positive nucleus forms the kernels and the valence electrons surround the positive kernel. This looks like a sea of electrons freely moving. Hence, the options A, B and C are not the particles forming the metallic solids.
Who among the following scientist belongs to solid state
Bravais is scientist who worked on Solid state.
The number of voids formed in hexagonal close packing arrangement is/ are ____.
In hexagonal close packing, two triangular voids are formed. Both the triangular voids face each other.
The most unsymmetrical crystal system is ____.
The cubic system is most symmetrical and triclinic is most unsymmetrical system, since the axial lengths are not equal and the axial angles are also not equal.
Schottky defect defines imperfection in the lattice structure of
Schottky defects are found in solid.
Metal deficiency defect is found in inorganic crystals such as ____ .
Metal deficiency defect is found in inorganic crystals such as iron oxide. Aluminium oxide and Sodium oxide compounds show point defect. Zinc oxide compound shows metal excess defect.
Potassium crystallizes with a
Potassium crystallises in BCC lattice.
The constituent particles in solids have ____ .
When the constituent particles are arranged in solid, they are fixed and their motion is arrested. They would have minimum energy due to the vibratory motion possible within the limited space available between two particles. All other motions are restricted.
Ferrimagnetic substance becomes paramagnetic when____.
When a ferromagnetic or anti-ferromagnetic solid is heated, it changes to paramagnetic solid. This is due to the randomisation of domains (spin of electrons) upon heating. Of the options listed, Ferrimagnetic substance becomes paramagnetic when the substance is heated at 850 K.
If a solid oxide ion is arranged in ccp, Cation A occupies 1/6th of tetrahedral voids and Cation B occupies 1/3rd of the octahedral void, then the formula of the compound is____.
Oxide ion occupies a ccp lattice. Hence, the number of oxide ions = 1 (occupies the corners of the cell). A occupies 1/6th of tetrahedral voids = 2 x 1/6 = 1/3 B occupies 1/3rd of octahedral voids = 1 x 1/3 = 1/3 Therefore, the formula would be A1/3B1/3O = A BO3
The co-ordination number of a metal crystallizing in a hexagonal close packed structure is
In hcp the coordination number is 12.
In fcc arrangement, the co-ordination number in the first layer is ____.
In a fcc structure, four atoms at the corners are close to the center atom on the face. In addition, there is one atom above and one below. Together, they form six in the first layer and twelve in the second layer.
AB, AB, AB,......... pattern is found in ____ elements.
Spectroscopic studies have revealed that Molybdenum and Magnesium have AB, AB, AB,......... pattern.
Diode is a combination of ____ type of semiconductors.
Diodes can be made either with n-type or p-type semiconductors. That is, it can be of electron rich impurity or electron deficit impurity. In either way, conduction is possible. Pure elements, like silicon, are made as semiconductors by heating and transferring the valence electrons to the conduction zone.
In a FCC solid, the atoms on the face contribute ____ to one unit cell.
In FCC, each face of the cube is shared by two cubes. Hence, the atom on the face would be contributing only one-half to each unit cell.
The different ways of close packing in two dimension are ____ .
The two different ways of two dimension packing are scp (square close packing) and hcp (hexagonal close packing).
Solids are formed by atoms which occupy a fixed position ____.
The atoms of a solid occupy fixed positions at low temperature, low thermal energy and when the intermolecular strength is strong. Solids are not formed by the arrangement of atoms only under one of the conditions.
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