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

Which of the following crystalline solids have the highest melting point?

  1. Covalent Solids

  2. Ionic Solids

  3. Molecular Solids

  4. Metallic Solids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Covalent network solid is a chemical compound in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material. In a network solid there are no individual molecules, and the entire crystal or amorphous solid may be considered a macromolecule

Melting point is high compared to others since melting means breaking covalent bonds (rather than merely overcoming weaker intermolecular forces).
Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

Statement: Covalent solids are good conductor of electricity.


State whether the given statement is true or false

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Covalent compound:
Covalent bonds are formed by sharing of electrons.they don't have a free electron that is required for electricity transfer (electricity is the flow of free electrons!) thus they are bad conductors but ionic compounds are a good conductor because of the presence of free electrons.

Hence, the given statement is false.
Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

Which of the following solids doesn't belong to the class of Covalent solids:

  1. Diamond

  2. Graphite

  3. Silicon Carbide

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

Diamond, graphite, and silicon carbide are classic examples of covalent network solids. Sodium chloride is an ionic solid held together by electrostatic forces between sodium and chloride ions.

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

Another name for Covalent solids is:

  1. Molecular Solids

  2. Atomic Solids

  3. Element Solids

  4. Compound Solids
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A Covalent network solid is a chemical compound in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material. In a network solid there are no individual molecules, and the entire crystal or amorphous solid may be considered a macromolecule.

Another name for covalent solids is Atomic solids.
Correct answer is option-B

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

Separate layers of covalent bonds are present in:

  1. Boron carbide

  2. Graphite

  3. Cadmium sulphide

  4. Aluminium nitride
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Graphite is a crystalline form of carbon and one of the allotropes of carbon. Graphite is the most stable form of carbon under standard conditions. It has a layered, planar structure. The individual layers are called graphene. In each layer, the carbon atoms are arranged in a honeycomb lattice with separation of $0.142 nm,$ and the distance between planes is $0.335 nm.$ Correct answer is option-B.

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

The major binding force of diamond, silicon and quartz is

  1. electrostatic force

  2. electrical attraction

  3. covalent bond force

  4. non-covalent bond force

  5. van der Waals' force
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The major binding force of diamond, silicon and quartz is covalent bond force.
For example, diamond is a covalent solid. It is a big giant network of $\displaystyle sp^3$ hybridised C atoms linked through strong covalent bonds.

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

Why is graphite used as a dry lubricant in machinery?

  1. Each carbon atom undergoes $sp^{3}$ hybridization in graphite

  2. Graphite has layered structure and its cleaves easily between the layers and therefore it is very soft and slippery

  3. Graphite is a non-conductor of electricity

  4. Graphite has two sigma bonds and two pi bonds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Graphite is a mineral made of loosely bonded sheets of carbon atoms, giving it a slippery texture that makes it a very effective lubricant.


Answer: Graphite has a layered structure and its cleaves easily between the layers and therefore it is very soft and slippery.

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

Which of the following compounds represent represent a normal $2 : 3$ spinel structure?

  1. $Mg^{II} Al _{2}^{III}O _{4}$
  2. $Co^{II} (Co^{III}) _{2}O _{4}$
  3. $Zn(TiZn) O _{4}$
  4. $Ni(CO) _{4}$
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

In $2:3$ spinel structure                                        General formula is $A^{+2}B _2^{+3}O _4$

$A^{+2} : \cfrac {1}{8}\times Tetrahedral\quad  voids$                    $B^{+3} : \cfrac {1}{2} \times Octahedral\quad voids$        $O^{2-}:FCC\quad lattice$

Only $Mg^{+2}Al _2^{+3}O _4$  and  $Co^{2+}(Co^{3+}) _2O _4$ satisfies the above conditions.

$\longrightarrow$ Also, in option (C) $Ti$ have $+4$ oxidtion state.

Ans-(A), (B)