Tag: chemistry

Questions Related to chemistry

Which substance exists as a molecular solid at ${20}^{o}C$?

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

  1. ${ CH } _{ 4 }$

  2. $Ba{ I } _{ 2 }$

  3. ${ H } _{ 2 }O$

  4. $P _4$

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Correct Option: D
Explanation:

At $20^\circ C$,


A) $CH _4$ is gas.
B) $BaI _2$ is Ionic solid.

C) $H _2O$ is liquid.
D) $P _4$ is molecular solid.


Answer: (D) $P _4$

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

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

  1. Covalent Solids

  2. Ionic Solids

  3. Molecular Solids

  4. Metallic Solids

Show answer
Correct Option: A
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).

Statement: Covalent solids are good conductor of electricity.


State whether the given statement is true or false

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

  1. True

  2. False

Show answer
Correct Option: B
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.

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

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

  1. Diamond

  2. Graphite

  3. Silicon Carbide

  4. Sodium Chloride

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Correct Option: D

Another name for Covalent solids is:

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

  1. Molecular Solids

  2. Atomic Solids

  3. Element Solids

  4. Compound Solids

Show answer
Correct Option: B
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

Separate layers of covalent bonds are present in:

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

  1. Boron carbide

  2. Graphite

  3. Cadmium sulphide

  4. Aluminium nitride

Show answer
Correct Option: B
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.

The major binding force of diamond, silicon and quartz is

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

  1. electrostatic force

  2. electrical attraction

  3. covalent bond force

  4. non-covalent bond force

  5. van der Waals' force

Show answer
Correct Option: C
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.

If we know the ionic radius ratio in a crystal of ionic solid, what can be known of the following?

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

  1. Magnetic property

  2. Nature of chemical bond

  3. Type of defect

  4. Geometrical shape of crystal

Show answer
Correct Option: D
Explanation:

Geomatrical shape of crystal can be calculated by knowing the radius ratio in a crystal of ionic solid.

Why is graphite used as a dry lubricant in machinery?

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

  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

Show answer
Correct Option: B
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.

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

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

  1. $Mg^{II} Al _{2}^{III}O _{4}$

  2. $Co^{II} (Co^{III}) _{2}O _{4}$

  3. $Zn(TiZn) O _{4}$

  4. $Ni(CO) _{4}$

Show answer
Correct Option: A,B
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)