In Class 12 Boards there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Downloads of CBSE Class 12 Chemistry Chapter 1 The Solid State Case Study and Passage-Based Questions with Answers were Prepared Based on the Latest Exam Pattern. Students can solve NCERT Class 12 Chemistry Case Study Questions The Solid State to know their preparation level.
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In CBSE Class 12 Chemistry Paper, There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.
The Solid State Case Study Questions With Answers
Here, we have provided case-based/passage-based questions for Class 12 Chemistry Chapter 1 The Solid State
Case Study/Passage-Based Questions
Case Study 1:In a hexagonal system of crystals, a frequently encountered arrangement of atoms is described as a hexagonal prism. Here, the top and bottom of the cell are regular hexagons and three atoms are sandwiched in between them. A space-filling model of this structure, called hexagonal close-packed (hep), is constituted of a sphere on a flat surface surrounded in the same plane by six identical spheres as closely as possible. Three spheres are then placed over the first layer so that they touch each other and represent the second layer. Each one of these three spheres touches three spheres of the bottom layer. Finally, the second layer is covered with a third layer that is identical to the bottom layer in a relative position.
(I) The number of atoms in this hep unit cell is
| (a) 4 | (b) 6 | (c) 12 | (d) 17 |
Answer: (b) 6
(ii) The empty space in this hep unit cell is
| (a) 74% | (b) 47.6% | (c) 32% | (d) 26% |
Answer:(d) 26%
(iii) In hexagonal close packing of spheres in three-dimensions
| (a) in one unit cell, there are six octahedral voids and all are completely inside the unit cell |
| (b) in one unit cell, there are six octahedral voids out of which three are completely inside the unit cell and the other three are from contributions of octahedral voids which are partially inside the unit cell |
| (c) in one unit cell, there are 12 tetrahedral voids, all are completely inside the unit cell. |
| in one unit cell there are 12 octahedral voids and all are completely inside the unit cell |
Answer:(a) in one unit cell, there are six octahedral voids and all are completely inside the unit cell
Case Study 2: In an assembly of atoms or molecules, a solid phase is formed whenever the interatomic attractive forces significantly exceed the disruptive thermal forces and thus restrict the mobility of atoms, forcing them into more or less fixed positions. From energy considerations, it is evident that in such solids the atoms or molecules will always attempt to assume highly ordered structures which are characterised by symmetry. Depending on the nature of the active interatomic forces, all solids may be subdivided into the following categories:
Ionic solids: These solids consist of positively and negatively charged ions arranged in a regular fashion throughout the solid. These solids are veryhard and brittle, have very high melting points and have high enthalpies of vaporisation, e.g., NaCl, MgO, KCl, LiCl etc.
Covalent solids: In these solids, the constituent particles are atoms which are linked together by a continuous system of covalent bonds. These bonds are strong and directional in nature. The covalent crystals are hard, have high melting points, are poor conductors of electricity. Diamond is a typical example of covalent solids.
Metallic solids : In these solids, the constituent particles are positive ions immersed in a sea of mobile electrons. Metallic solids may be hard as well as soft. They are good conductors of heat and electricity e.g., common metals such as nickel, copper and alloys.
Molecular solids : In these the constituent particles are molecules. The molecules are held together by dispersion forces or London forces, dipole-dipole forces or hydrogen bonds.
In these questions (Q. No. i-iv), a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
(i) Assertion: Molecular solids are characterized by low melting point.
Reason: Molecular solids are made up of covalent molecules.
Answer:(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(ii) Assertion: Ionic solids are characterized by high melting and boiling point.
Reason: Ionic solids have coulombic forces of attraction between their ions.
Answer:(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(iii) Assertion: Covalent solids are insulators of electricity.
Reason: Covalent solids are constituted by ions.
Answer:(c) Assertion is correct statement but reason is wrong statement.
(iv) Assertion: Diamond and graphite do not have the same covalent structure.
Reason: Silicon carbide is typical example of network solid.
Answer:(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
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