Assertion & Reason Type Questions: The Solid State | Chemistry Class 12 - NEET PDF Download

Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Question 1: Assertion (A): Most of the solids possess high melting point.
Reason (R): They have strong intermolecular forces of attraction.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.
(e) Assertion and Reason both are false.

Correct Answer is Option (a)
Most of the solids possess high melting point due to the presence of intermolecular forces of attraction between their particles.

Question 2: Assertion: For fluorite structure, the F^– ions occupy tetrahedral void, but Ca⁺² ions occupy c.c.p.
Reason: The radius ratio of fluorite structure is 0.225.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.
(e) Assertion and Reason both are false.

Correct Answer is Option (c)

Assertion is true but Reason is false.
In flourite structure, the F⁻ ions occupy tetrahedral voids and Ca²⁺ ions form cubic closed packing. Each Ca²⁺ is surrounded by 8F⁻ ions and it has a coordination number of 8 whereas each F⁻ ion is surrounded by 4 Ca²⁺ ions and it has a coordination number of 4. Thus, this structure has 8:4 coordination. The radius ratio of fluorite structure is usually more than 0.732.

Question 3: Assertion (A): Amorphous solids possess a longrange order in the arrangement of their particles.
Reason (R): The formation of amorphous solids involves very rapid cooling.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.
(e) Assertion and Reason both are false.

Correct Answer is Option (d)

Amorphous solids do not possess a long-range order in the arrangement of their particles because their formation involves rapid cooling.

Question 4: Assertion: Diamond is a precious stone.
Reason: Carbon atoms are tetrahedrally arranged in diamonds.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.
(e) Assertion and Reason both are false.

Correct Answer is Option (b)

Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
It is true that in the diamond structure, carbon atoms are arranged tetrahedrally (sp3 hybridized) but it is not the correct explanation of assertion.

Question 5: Assertion (A): Crystalline solids are anisotropic in nature.
Reason (R): Some of their physical properties show same electrical and optical properties in different directions in the same crystal.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.
(e) Assertion and Reason both are false.

Correct Answer is Option (C)
Crystalline solids are anisotropic in nature as some of their physical properties show different electrical and optical properties in different directions in the same crystal.

Question 6: Assertion: The total number of atoms present in a simple cubic unit cell is one.
Reason: Simple cubic unit cell has atoms at its corners, each of which is shared between eight adjacent unit cells.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.
(e) Assertion and Reason both are false.

Correct Answer is Option (a)

Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
In a simple cubic unit cell, only corners are occupied by atoms. Thus, the total number of atoms present in the unit cell will be one. 8 × 1/8 = 1.

Question 7: Assertion (A): Graphite is a good conductor of electricity; however, diamond belongs to the category of insulators.
Reason (R): Graphite is soft in nature, on the other hand diamond is very hard and brittle.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.
(e) Assertion and Reason both are false.

Correct Answer is Option (B)

Diamond is a bad conductor of electricity because all valence electrons of carbon are involved in bonding. In graphite, however 3 out of 4 valence electrons are involved in bonding and the fourth electron remains free between adjacent layers which makes it a good conductor. Graphite is soft because parallel layers are held together by week vander Waals forces. However, diamond is hard due to compact three dimensional network of bonding.

Question 8: Assertion: Graphite is a good conductor of electricity however diamond belongs to the category of insulators.
Reason: Graphite is soft in nature on the other hand diamond is very hard and brittle.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.
(e) Assertion and Reason both are false.

Correct Answer is Option (b)
Assertion and reason both are correct statements but the reason is not the correct explanation for assertion.

The correct explanation for reason is, In graphite, carbon atoms are arranged in different layers and each atom is covalently bonded to three of its neighboring atoms in the same layer. The fourth electron is free to move which makes graphite a good conductor.

Question 9: Assertion (A): Total number of octahedral  voids present in unit cell of cubic packing including the one that is present at the body centre is four.
Reason (R): Besides the body centre  these is one octahedral void present at the centre of each of the 4 faces of the unit cell and each of which is shared between two adjacent unit cells.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.
(e) Assertion and Reason both are false.

Correct Answer is Option (C)
Total number of octahedral  voids present in unit cell of cubic packing including the one i.e., present at the body centre, is four.

Question 10: Assertion: Electrical conductivity of semiconductors increases with increasing temperature.
Reason: With the increase in temperature, a large number of electrons from the valence band can jump to the conduction band.
(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.
(e) Assertion and Reason both are false.

Correct Answer is Option (a)
Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
The electrical conductivity of solids is due to the motion of electrons and holes or ions.

Conduction of ionic solids is due to the absence of vacancies and other defects. Thus, the conductivity of semiconductors, as well as insulators, is mainly because of impurities and defects present in them. Electrons and holes produced by the ionization of defects contribute to conduction in these solids.

The electrical conductivity of semiconductors increases with increasing temperature because, with an increase in temperature, the number of electrons from the valence bond can jump to the conduction band in semiconductors.