NCERT Solutions for Class 12 Chemistry Chapter 1 – The Solid State

NCERT Solutions for Class 12 Chemistry Chapter 1 – The Solid State are carefully drafted by best chemistry experts. This chapter tells you that we encounter solid things in a large number, so we need to understand the properties of solids to use them accordingly. It also tells you that solids can be divided into amorphous solids and crystalline solids depending upon the properties they show. This chapter of NCERT Solutions elaborates about the different types of arrangements of constituent particles in crystalline solids and some calculations related to it. It also tells you about the defects in solid crystals and their electrical and magnetic properties. 

There are a total of 26 questions asked at the end of the chapter covering all the concepts taught in NCERT CBSE Class 12 Chemistry Chapter 1. The questions given in the chapter enable you to revise the learnt concepts thoroughly.

All of these questions are answered in a detailed manner in Class 12 Chemistry Chapter 1 – The Solid State. They follow all the guidelines given by CBSE and NCERT. The solutions are written in an in-depth manner covering all aspects of the chapter. These are precise solutions that help you learn effectively.

NCERT Class 12 Chemistry Chapter 1

NCERT Solutions for Class 12 Chemistry Chapter 1 – The Solid State covers all the important concepts of the unit. They give you an in-depth understanding of each concept covered in the chapter. Some concepts covered in this chapter have been given below.

  • General Characteristics of Solid State

This part of the chapter tells you about the characteristic properties of solids. It tells you that they have definite mass, volume, and shape; their intermolecular distances are short and intermolecular forces are strong. It also tells you that their constituent particles have fixed positions and are allowed only to oscillate about their mean positions. They are incompressible and rigid. 

  • Amorphous and Crystalline Solids

This part of the chapter tells you that crystalline solids have definite geometrical shape, a characteristic melting point, sharp cleavage property, characteristic heat of fusion, long-range order and are anisotropic in nature. It also tells you that amorphous solids have an irregular shape, no sharp melting point, an uneven edge when cut with a sharp edge tool, no definite heat of fusion and short-range order. 

  • Classification of Crystalline Solids

This chapter teaches you that crystalline solids are classified into four categories according to the nature of intermolecular forces operating within them. They are molecular solids, metallic solids, ionic solids, and covalent or network solids whose constituent particles are molecules, positive ions in a sea of delocalized electrons, ions and atoms respectively. 

  • Crystal Lattices and Unit Cells

This part of the chapter tells you that crystal lattice is the definite three-dimensional arrangement of particles of a crystal in space. It also tells you that there are 14 such arrangements possible known by the general name of Bravais Lattices. 

This chapter further teaches you that the unit cell is that smallest entity of a crystal, which, when added in different directions, can grow to give the entire lattice. It is characterized by its edges (a, b and c which may or may not be perpendicular) and angles between the edges (α, β and γ). 

This chapter also explains that unit cells can be divided into centred [body centred (bcc), face centred (fcc) and end centred] and primitive types (seven types). 

  • Number of Atoms in a unit cell

In this section, you learn that the total number of per unit cells of a primitive cubic unit cell is calculated to be 1. For bcc type, it is 2, and for fcc it is 4 atoms per unit cell. 

  • Closed Packed Structures

In this part of the chapter, you learn how a crystal can be closely packed in one, two and three dimensions to give different types of three-dimensional structures. 

It further tells you about tetrahedral and octahedral voids developed in between the layers of constituent particles during three-dimensional packing. Hexagonal close packing (hcp) and cubic close packing (ccp) are the most efficient packing systems.  

  • Packing Efficiency

This portion from the first chapter of CBSE NCERT Class 12 Chemistry book tells you that there is always some free space left between constituent particles after close packing. It is depicted as a percentage of total space filled by the particles and is known as packing efficiency. Packing efficiency of hcp and ccp packing is 74%, and in bcc and simple cubic lattice, it is 68 and 52.4 % respectively.

  • Imperfections in solid

Here you learn that crystalline solids contain some anomalies in the structure known as a point (around a point in crystal) and line defects (in the whole row). Point defects can be of three types known as stoichiometric, impurity and non-stoichiometric defects. 

It further tells you that stoichiometric defect does not disturb the stoichiometry of crystals. Vacancy and interstitial, the two basic types of defects can be shown by non-ionic solids and Frenkel, and Schottky defects are shown by ionic solids. 

Here you will also learn that Impurity defect is brought about by the presence of any impurity in the crystal. This chapter also elaborates about how metal excess and metal deficient are the two types of non-stoichiometric defects. 

  • Electrical properties 

This part of the chapter deals with using properties of defects in making semiconductors for improved electrical properties of crystalline substances. This is done by doping impurities into a crystal to prepare p-type and n-type semiconductors.

  • Magnetic Properties 

This part of the chapter tells you that every substance has some magnetic properties associated with it and on this basis, they can be classified into five categories namely, paramagnetic, diamagnetic, ferromagnetic, ferrimagnetic and antiferromagnetic. These properties are used in making a video, audio and recording gadgets.  

CBSE NCERT Class 12 Chemistry Chapter 1 Exercise

Our NCERT Solutions for Chapter 1 – The Solid State consists of 26 questions covering the important concepts learnt in CBSE NCERT Class 12 Chemistry Chapter 1 The components of the exercise have been listed below. 

  • Questions 1 is a direct question asking you about amorphous solids. 
  • Questions 2 and 3 are memory-based questions asking you to separate the given items in various types of solids.
  • Questions 4 is based on the coordination number concept.
  • Question 5 is a numerical asking to calculate the atomic mass of metal using its unit cell information. 
  • Questions 6 asks you to relate and comment on how the physical properties of a crystal are dependent on intermolecular forces.
  • Question 7 is a differential question asking to distinguish between a given pair of terms.
  • Questions 8 and 10, 21, 24 are based on properties of unit cells in different packing types.  
  • Question 9 is a direct question on the metallic and ionic crystals.
  • Questions 11 to 16,18, 19 are numerical questions based on properties of a unit cell.
  • Questions 17, 20, 22 are direct questions on semiconductors. 
  • Question 23 is a direct question on different defect types. 
  • Question 25 is numerically based on defects.
  • Question 26 is a direct question and asks the definitions of different magnetic properties in solids. 

This chapter also comprises 24 intext questions that comprehensively cover all topics from this chapter. Our NCERT Solutions for Chapter – ‘The Solid State’ answer all the intext questions precisely yet in detail.

Benefits of NCERT Solutions for Class 12th Chemistry Chapter 1 – The Solid State 

Some of the key benefits of learning and revising from NCERT Solutions for Class 12 Chemistry Chapter 1 – The Solid State are listed below.

  • They deal with the basic information of crystalline solids and their properties and help you become thorough with the fundamental concepts of the chapter. 
  • They are to the point, fully accurate and facilitate speedy and effective learning.
  • They let you know how to solve related problems that can be asked in your board exams and various competitive exams.
  • The solutions given provide a comprehensive outlook of the topics covered in the chapter and at the same time prepare you for scoring high in class 12th board exams. 
  • They make learning a fun, fascinating and enjoyable process.