Solid State MCQ: Definition, Characteristics & Types

Ans. b) Study of the synthesis, structure, and characteristics of solid phase materials.

Explanation: Solid-state chemistry, which is often known as materials chemistry, refers to the study of the synthesis, structure, and characteristics of solid phase materials, predominantly of the non-molecular solids. More significantly, in solid-state chemistry, the concept of a compound on a deeper level is studied which helps us to understand the compound starting from a molecular level perspective to the crystal structure level perspective.

Ans. c) Both a & b

Explanation: On the basis of the nature of order present in the arrangement of their constituent particles, solids can be classified as either crystalline or amorphous.

Crystalline solids: They have sharp melting points and start melting when they reach a particular temperature. The shape of crystalline solids are definite in nature and they possess typical arrangements of particles. Furthermore, they demonstrate the property of cleavage (that is, when they are cut with the edge of a sharp tool they split into two pieces and the newly generated surfaces are smooth and plain).

Crystalline solids have a definite heat of fusion (amount of energy needed to melt a given mass of solid at its melting point). They are anisotropic (refers to the physical properties such as electrical resistance or refractive indices which demonstrate different values when they are measured along different directions in the same crystal). In addition to the above properties, crystalline solids are true solids.

Amorphous solids: They become softer gradually over a range of temperatures and they can be moulded into different shapes on heating. They are pseudo-solids or super-cooled liquids which means they have a tendency to flow very slowly.

Amorphous solids have irregular shapes, that is, their constituent particles do not have definite geometry of arrangements. When amorphous solids are cut with a sharp-edged tool, it results in the formation of pieces with irregular surfaces. They do not have definite heat of fusion due to the irregular arrangement of the particles. Furthermore, amorphous solids are isotropic in nature (the value of any physical property would be the same along any direction because of the irregular arrangement of particles).

Ans. a) Solid state

Explanation: Ice is the solid state of water, which is generally a liquid that freezes to a solid at temperatures below 0 degrees Celsius (32°F). At temperatures which are below 0°C (32°F), the water vapour forms frost at ground level as well as snowflakes (each consisting of a single ice crystal) in the clouds. However, below the same temperature, the liquid water forms a solid, as, for instance, river ice, hail, and ice produced commercially or even in household refrigerators.

Ans. b) Gaseous state

Explanation: The gaseous form represents the third state of water (in the form of water vapour). In gaseous state, water molecules are able to travel quickly and are not bonded together.

Water vapour is formed either via the process of evaporation (refers to the process where a water molecule leaves the surface and diffuses into the surroundings. Each individual water molecule which undergoes this transition does so through the process of either absorption or release of kinetic energy) or sublimation (refers to the process by which molecules directly convert into vapour without passing through liquid phase).

Ans. d) Refers to the existence of substance in more than one of the gaseous modifications

Explanation: Polymorphism is a condition in crystallography wherein a solid chemical compound exists in different crystalline forms and each has different physical and chemical properties, but form identical solutions and vapours.

Among polymorphs (different crystalline forms of the compound) of certain compounds, it is observed that one is relatively more stable than the others under all conditions. However, in some other cases, one polymorph is stable within a particular range of temperature and pressure while the other is stable under different sets of conditions.

Ans. d) 1000 to 1500

Explanation: Solids normally do not react at room temperature and it is required to heat them at much higher temperatures, often 1000°C to 1500°C, in order for a reaction to occur at an appreciable rate.

Furthermore, during the process of solidification of polycrystalline materials, small nuclei are initially formed at different positions of the liquid having relatively random crystallographic orientations. However, these small nuclei grow into larger crystals by the absorption of atoms present in the surrounding liquid leading to formation of polycrystalline solids.

Ans. c) Thermodynamic and kinetic factors

Explanation: In solid state reactions, the thermodynamic factors demonstrate whether or not a particular reaction should occur by analysing the changes occurring in the free energy which will be involved in the reaction as well as the kinetic factors which will ultimately determine the rate at which the reaction occurs.

Solid-state reactions are fairly commonly used as a synthesis method to obtain polycrystalline material from solid reagents. For this reaction to occur, high temperatures are usually employed.

Furthermore, the factors that also affect solid-state reactions are chemical and morphological properties of the reagents including the reactivity, surface area, and free energy change with the solid-state reaction, and other reaction conditions, such as the temperature, pressure, and the environment of the reaction.

Ans. b) The surface area of a solid is observed to increases with decrease in the particle size

Explanation: Surface area is inversely related to particle size. For instance, in the form of a single crystal, a few grams of a solid has a surface area which might be equal to the area of, say, a large postage stamp. But, in the form of a finely divided powder, its surface area is almost equivalent to the area of a hundred-metre running track. Hence, it can be concluded that the surface area increases with a decrease in particle size.

Ans. a) Gases react faster than the solids

Explanation: Reactions which occur in phases that easily mix, such as gases and liquids, inherently occur much faster than those reactions which occur between solids. The extent of mixing of the reactants ultimately influences the frequency of molecular collisions, that is, if the reactants are more thoroughly mixed, the molecules will collide more often and will thus react faster. Therefore it can be concluded that gases react at a much quicker rate than solids because the mobilities of the constituent particles in gases are more. 

Ans. c) Aqueous solution, melt, glass or gel

Explanation: Crystallisation refers to the process by which solid forms because of the organisation of the atoms or molecules in clusters into a structure known as a crystal. The crystallisation process consists of two major events, nucleation and crystal growth which are driven by thermodynamic properties as well as chemical properties

Aqueous solution, melts, glass or even gel, is usually present as a homogenous, single phase and amorphous solid. Because of these properties, it may result in facilitating the formation of crystalline products, since long range diffusion of ions may not be necessary and the product may form at lower temperatures. Thus, making them ideal starting materials for the process of crystallisation.