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Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

The thermal conductivity of silver and copper is high because they have following binding :

  1. Metallic

  2. Ionic

  3. Covalent

  4. Vander Waal
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The thermal conductivity of silver and copper is high because they have metallic bonding.


Silver and copper are metals. They form metallic bonds. They contain mobile electrons immersed in a sea of positively charged metal cations. 

These mobile electrons can move from one end of metal to other end. Hence, they conduct electricity.

Therefore, option A is correct.

Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

Metallic bonding is explained by :

  1. band model

  2. electron-sea model

  3. both (a) and (b)

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Both theories have their own arguments to explain metallic bonding.
Each metal atom allows its electrons to roam freely, so these atoms become positively charged cations. These cations are kind of like a positively charged island and are surrounded by a sea of negatively charged electrons.

Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

Some of the following properties are important in determining whether an element has metallic properties.
I : atomic number
II : atomic weight
III: number of valence electrons
IV: number of vacant atomic orbitals
V: total number of electronic shells in the atom
Select correct properties from the codes given below:

  1. I, II, III, IV

  2. I, III, IV, V

  3. III, IV

  4. III, IV, V
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The following properties are important in determining whether an element has metallic properties.
III: number of valence electrons
IV: number of vacant atomic orbitals
All metals are electropositve elements and have a tendency to lose electrons.  Alkali metals and alkaline earth metals contain one and two valence electrons respectively.They readily lose these electrons and show metallic properties. Transition metals have a number of vacant d orbitals and show variable valency. Due to the presence of vacant d orbitals, they show variable valence.

Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

A solid melt slightly above $273K$ and is a poor conductivity of heat and electricity. To which of the following categories does it belong?

  1. Ionic solid

  2. Covalent solid

  3. Metallic solid

  4. Molecular solid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A solid with a low melting point (near 273K) and poor conductivity is characteristic of a molecular solid, where molecules are held by weak intermolecular forces.

Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

Which of the following is an example of molecular solid?

  1. Zinc Sulphide

  2. Magnesium Oxide

  3. Dry ice

  4. Diamond
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Molecular solids refer to those solids which are composed of molecules held together by the van der Waals forces. 

Examples are hydrogen, carbon dioxide etc.

ZnS is a crystalline solid.
MgO is an ionic solid.
Diamond has a network structure.

Hence, dry ice $(CO _2)$ is an example of a molecular solid.

Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

A solid melts slightly above $273$ K and is a poor conductor of heat and electricity. To which of the following categories does it belong?

  1. Ionic

  2. Covalent

  3. Metallic

  4. Molecular
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Metals are good conductors of heat and electricity with variable melting points.
Ionic solids are also good conductors of heat and electricity with very high melting points.
Covalent solids are non conductor of electricity and heat with very high melting points due to their strong bonding.
Molecular solids are poor conductors of heat and electricity and they have lower melting point than ionic solids.

Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

Molecular crystals exists in:

  1. crystalline state

  2. amorphous state

  3. non-crystalline state

  4. None of the above
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Molecular crystals exist in all crystalline state, an amorphous state, and non-crystalline state. Molecular crystals are substances that have relatively weak intermolecular binding, such as dry ice (solidified carbon dioxide), solid forms of the rare gases (e.g., argon, krypton, and xenon).

Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

Metallic solids are always opaque because:

  1. they reflect all the incident light

  2. they scatter all the incident light

  3. the incident light is readily absorbed by the free electrons in a metal

  4. the energy band traps the incident
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Metals are opaque because they have metallic bonding which means that all of the atoms are surrounded by free-moving electrons.


The incident light on metals is absorbed by large numbers of available free electrons in metals to increase their kinetic energy and hence they are opaque.