JEE Questions for Chemistry The Solid State Quiz 2 - MCQExams.com

For ionic solids, the ration of the radius of cation to that of anion is called radius ration.

For bcc structure, the radius ratio should be greater than 0.73. because radius ratio lies between 0.732 to 1.00.

The coordination number of octahedral geometry is 6. Whose radius ratio lies between 0.732 to 0.414 

The density of crystal is lowered in schottky defect because, in schottky defect equal number of cations and anions are missing from the lattice, so the electrical neutrality is maintained and as number of cations and anions are missing so mass will decrease.

We know that,

Density = mass/ volume

So density is directly proportional to mass, so due to decrease in mass, density will also decreases.

Pentavalent impurity mixed in germanium give n-type semiconductor.

A schottky defect is a type of point defect in a crystal lattice. In non – ionic crystals it means a lattice vacancy defect.
  In ionic crystals, the defect forms when oppositely charged ions leave their sites, creating vacancies. There vacancies are formed in stoichiometric units, to maintains an overall neutral change in the ionic solid. The vacancies are then free to move about their own entities. Normally these defects will lead to a decrease in the density of the crystal.

Schottky defects occurs mainly in high electrovalent compounds where the positive and negative ions are of the same size and hence the coordination number is high.

The Frenkel defect is a defect in the lattice crystal where an atom or ion occupies a normally vacant site other than its own .As a result the atom or ion leaves its own lattice site vacant.

The flame colors of metal ions are due to metal excess deffective. There type of defects seen because of missing of anions from regular site leaving a hole which is occupied by electron to maintain the neutrality of the compound. Hole occupied by electron is called F – centre and responsible for showing colour by the compound.

1. Silicon doped with boron is a p-type semiconductor.
2. Silicon doped with arsenic is a p-type semiconductor.
3. Metals are good conductors of electricity.
4. The electrical conductivity of a semiconductor increases with increase in temperature because with increase in temperature the electrons overcome the energy barrier between the valence bond and the conduction bond easily.

Iodine, sulphur and phosphorus exists as I₂, S₆ and P₄ respectively. Silicion does exist as covalent crystal in the solid state, because in silicon, constituent particles are bonded together by covalent bons.

Quartz (SiO₂), or silicon dioxide also known as silica has a gaint covalent structure.
In SiO₂, each silicon atom is covalently bonded to four oxygen atoms. Each oxygen atom is covalently bonded to two silicon atoms.