Solid State Test - 2

• Ionic solids or compounds are formed by the transfer of electrons from one atom to another atom.
• Hence there is always the formation of anion and cation due to opposite charges electrostatic force of attraction formed between them which holds them together.

Therefore, the correct answer is B.

Diamond has a very high melting point (almost 4000°C) due to very strong carbon-carbon covalent bonds having to be broken throughout the structure before melting occurs. 

Explanation: 

• Each carbon atom is covalently bonded to four other carbon atoms in a diamond.
• A lot of energy is needed to separate the atoms.
• This is because covalent bonds are strong.
• This is the reason why diamond has a high melting point.

• Amorphous solids are isotropic in nature.
• The structure of amorphous solids is similar to that of liquids.
• Hence, these are also called pseudo solids or supercooled liquids.
• Isotropy of amorphous solids is due to the same irregular arrangement of constituent particles along with all the directions.
• Cotton candy is a classic example of amorphous solids. 

• Basic particle forming ice crystals are water molecules. It is a molecular crystal.

• Water molecules are arranged in a cage-like structure orderly array resulting in a crystalline structure.

• Crystalline compounds are made up of particles or molecules that are organized in a specific order, such as ice particles or water molecules, resulting in an ordered structure known as a crystalline compound.

• Crystalline solids are anisotropic in nature, that is, some of their physical properties like electrical resistance or refractive index show different values when measured along with different directions in the same crystals.
• This arises from different arrangements of particles in different directions.

• Due to the random organization of particles, amorphous solids have the same physical properties along with all directions or are isotropic.
• Random organization of particles also results in unequal bond strengths.
• Upon cooling, amorphous solids turn into a brittle glass-like state from a flexible rubber-like state. This is called glass transition.

Hence, the correct answer is Glass transition.

A diamond is not considered a molecule because each carbon atom is covalently bonded with four other carbon atoms. This is what makes a diamond a network solid.

Additional Information: 

• A network solid or covalent network solid (also called atomic crystalline solids) is a chemical compound (or element) in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material. 
• Examples of network solids include diamond with a continuous network of carbon atoms and silicon dioxide or quartz with a continuous three-dimensional network of SiO₂ units.

Molecular solids consist of atoms or molecules held to each other by dipole-dipole interactions, London dispersion forces, hydrogen bonds, or any combination of these. 

Additional Information: Hydrogen bonding refers to the formation of Hydrogen bonds, which are a special class of attractive intermolecular forces that arise due to the dipole-dipole interaction between a hydrogen atom that is bonded to a highly electronegative atom and another highly electronegative atom which lies in the vicinity of the hydrogen atom. 

• An amorphous or non-crystalline solid is a solid that lacks the long-range order that is characteristic of a crystal.
• In brief, an amorphous solid is any noncrystalline solid in which the atoms and molecules are not organized in a definite lattice pattern. Such solids include glass, plastic, and gel.
• Quartz glass (SiO₂) is an amorphous solid due to its short range order of constituent particles. Note Quartz is a crystalline solid while quartz glass is an amorphous solid.

• We know that glass is an amorphous solid and by alternate heating and cooling, it can be converted to crystalline forms.
• Glasses of ancient monuments undergo heating due to the exposure of sun (day time) and cool at night and thus converted to partly crystalline form.
• This results in a milky appearance.