Solid State MCQs

Ice is the only substance that has a lower density as a solid than as a liquid. Its density is 0.92 g/cm3 as a solid and 1 g/cm3 as a liquid. Mercury has a density of 14.184 g/cm3 as a solid and 13.69 g/cm3 as a liquid. Carbon dioxide has a density of 1.56 g/cm3 as a solid and 1.10 g/cm3 as a liquid. NaCl has a density of 2.71 g/cm3 as a solid and 1.556 g/cm3 in molten state.

Crystalline solids are homogeneous in composition, meaning that the composition of the solid is uniform throughout. Additionally, crystalline solids are anisotropic, meaning that the values of physical properties change with direction throughout the body of the solid.

Polymorphous is when a single substance can crystallize in two or more forms depending upon the conditions. Isomorphous is when two or more substances have the same crystal structure.

Quartz glass does not have a perfectly ordered structure, hence it is classified as an amorphous solid. The rest are crystalline solids due to ordered structures.

Amorphous solids behave like fluids and flow very slowly under the influence of gravity. Therefore, they are considered to be supercooled liquids.

Crystalline solids have a perfectly ordered structure which collapses immediately at a specific temperature. Amorphous solids melt over a range of temperatures, not one specific value.

The intermolecular forces of attraction in a solid are very strong, making it incompressible. Gases are highly compressible, while liquids are semi-compressible.

A unit cell is the basic repeated structural unit of a crystalline solid. It is composed of many small crystals, each of which is called a unit cell. Monomer is the basic unit for a polymer, and atoms make up molecules, which can further arrange themselves to form solids, liquids or gases.

An amorphous solid has short range order present which is independent of the temperature. Long range order is present in crystalline solids.

There are two polymorphous structures of sulfur, rhombic and monoclinic. Polymorphous structures occur when a single substance can crystallize in two or more forms depending upon the conditions.

Molecular solids are solids that are collections of molecules held together by intermolecular forces. In polar molecules such as HCl, So2, etc., the molecules are held together by dipole-dipole interactions, which is the attraction between the positive and negative ends of the molecules.

Diamond is an example of a covalent solid, which is a type of solid in which the constituent particles are attached to each other by covalent bonds. Examples of covalent solids include diamond, graphite, silicon, SiC, AIN, and quartz.

Silicon is found in nature in the form of a network solid due to its catenation property. Catenation is the ability of an atom to form bonds with other atoms of the same element. The compounds of silicon are reactive and not stable.

A cubic crystal has three equal dimensions, a = b = c, and three angles, α = β = γ = 90. This is because a cubic crystal is a symmetrical structure, with each side of the cube being equal in length and each angle being equal in measure. The angles of a cube are all right angles, meaning that the measure of each angle is 90 degrees.

Hexaclinic is not a crystal system. The other crystal systems are cubic, tetragonal, rhombohedral or trigonal, orthorhombic or rhombic, monoclinic, triclinic and hexagonal.

The face-centred cubic cell is a type of unit cell in which atoms are present at the corners and faces of the unit cell. In this type of unit cell, a unit cell is shared equally by six unit cells.

Orthorhombic crystal system is characterized by three axes of unequal length and all perpendicular to one another. It is also known as rhombic crystal system and examples of orthorhombic crystals include topaz and barite.

The most unsymmetrical crystal system is the triclinic crystal system, in which all three axes are unequal in length and none of them is perpendicular to another. Triclinic unit cells have the least symmetrical shape of all unit cells, and turquoise is an example of a triclinic crystal.

The unit cell in which the constituent atoms are present only at the corner is known as simple cubic cell. It is also referred to as a primitive cubic cell. In the simple cubic cell, each corner atom is shared by eight different unit cells.

Lattice points are the points at which atoms may be present on the unit cell. They indicate the position of atoms in a crystal.

Monoclinic crystal systems are characterized by three axes of unequal length and two axes that are perpendicular to each other. Examples of monoclinic crystals include gypsum and borax.

Metallic crystals are composed of metal cations surrounded by a sea of mobile valence electrons. These electrons are able to move through the entire crystal, allowing the metallic crystals to conduct both heat and electricity.

Crystalline solids are anisotropic, meaning they have different properties in different directions, whereas amorphous solids are isotropic, meaning they have identical properties in all directions. The lack of a clean cleavage, true solidity, and sharp melting points are all characteristics of crystalline solids.

Amorphous solids are isotropic, meaning they have identical properties in all directions. The other options are characteristics of crystalline solids.

Solids are classified as crystalline and amorphous solids based on their crystal structures. In crystalline solids, the constituent particles are arranged in a regular manner, while in amorphous solids, the constituent particles are not arranged in any regular manner.

Quartz is a common example of covalent solids. In covalent solids, the constituent particles are attached to each other by covalent bonds. Diamond, graphite, silicon are other examples of covalent solids.

Solid CO2 is an example of molecular crystal. These solids have molecules as their constituent particles. These solids may be bonded by vander waals’ forces or by dipole-dipole attraction or by strong hydrogen bonds. H2, Cl2, I2 are some examples of molecular solids.