Important Questions Class 12 Chemistry Chapter 1

Important Questions Class 12 Chemistry Chapter 1

Important Questions for CBSE Class 12 Chemistry Chapter 1 – The Solid State

Important Chemistry Class 12 Chapter 1 questions are designed to help students gain a thorough understanding of the topics. These also help students in revising and practising for upcoming tests. Solid-state Class 12 Important Questions are prepared to give students a better understanding of the types of questions they can expect in their exams. The questions are available both online and offline. Students can go over the notes or practise the questions at their convenience.

This chapter is about the solid state of matter. Solid-state properties, classification and other details are thoroughly explained here. To improve their scores, students go over the chapter notes and then practise the solid-state Class 12 Important Questions provided here. Students are given a well-explained summary of Chemistry Class 12 Chapter 1 as well as important questions.

CBSE Class 12 Chemistry Chapter-1 Important Questions

Study Important Question for Class 12 Chemistry Chapter 1 – The Solid State

Q1. Why are amorphous solids isotropic in nature?

A. Because amorphous solids have an uneven particle arrangement in all directions, the value of each physical property is the same in all directions. They are therefore isotropic.

Q2. Define the concept of voids.

A. The spaces between the constituent particles of a substance are referred to as the void in its literal sense. The void is the unoccupied or empty space within a unit cell.

Q3. What is the number of coordination for-

(a) An octahedral void

(b) A tetrahedral void

A. (a) An octahedral void has a coordination number of 6.

(b)The coordination number of a tetrahedral void is 4.

Q4. Current is said to flow through holes in a p-type semiconductor. Explain.

A. An electric current is created when electrons pass through a substance. In order to do so, the electron must be able to enter a ‘hole’ in the substance. In p-type semiconductors, there are more electrons than holes. A current can only travel in one direction along with the material.

Q5. Define the term “F-centre.” Mention one of its consequences.

A. An F-centre, FARBE centre, or colour centre is a crystallographic defect in which one or more unpaired electrons occupy an anionic vacancy in a crystal (from the German Far Zentrum). These vacancies absorb visible spectrum light, turning normally clear materials into colourful ones. As a result, it is employed in the detection of a wide range of chemicals, including zinc oxide.

Q6. Why is graphite a soft lubricant and a good electrical conductor?

A. Graphite, a soft lubricant, is an excellent electrical conductor because its electrons are delocalised and free to move around in the crystal structure. Graphite has a large number of free electrons in addition to being an excellent conductor of electricity.

It is made up of only carbon.

Q7. Explain how many atoms are located at the following locations of a cubic unit cell(a) corner, (b) body centre, (c) face centre and (d) edge centre.

A. (a)- Eight neighbouring cubic unit cells share the same atom in the corner. As a result, one unit cell represents 1/8th of the atom.

(b)- Each unit cell in a cubic unit cell has its own atom in the body centre, which is not shared with the unit cell next to it. The contribution of an atom to the unit cell is one due to its presence in a single unit cell.

(c)- Six neighbouring unit cells on the face of a cubic unit cell share the same atom. As a result, one unit cell represents one-half of an atom.

(d)- The edge of a cubic unit cell is always shared by four unit cells at the same time. Each unit cell will receive 1/4th of an atom at the edge centre.

Q8. What exactly is a non-stoichiometric defect? Colour develops in ionic solids with anionic vacancies caused by a metal excess defect. Explain using appropriate examples.

  1. Non-stoichiometric flaws are imperfections that do not affect the stoichiometry of a crystalline substance. The electrons in the anionic sites cause the colour to develop. These electrons become excited as a result of absorbing energy from visible light. When NaCl crystals are heated in an environment of sodium vapours, they produce NaCl. The Na atoms on the surface lose their electrons and form Na+ ions during this phase, while the liberated electrons diffuse inside the crystal to fill the unoccupied anionic sites. They are stimulated when they absorb visible light energy and give a yellow colour.

Q9. Explain each of the following terms using one example:

  1. Ferrimagnetism
  2. Antiferromagnetism
  3. 13-15 compounds

Ans: (a)- Ferrimagnetism: Ferrimagnetic substances contain magnetic moments in unequal amounts aligned in parallel and antiparallel orientations. MgF2O4 and ZnFe2O4 are two examples of ferrites. Magnesium is more strongly attracted to ferrimagnetic materials than to ferromagnetic materials. When heated, these compounds become paramagnetic.

(b) Antiferromagnetic compounds have comparable domain structures to ferromagnetic substances due to their opposite orientation. The magnetic moments of domains that are opposed to each other cancel out.

(c) Compounds of the 13-15 group are created by combining 13-15 group components. These chemicals are made to promote the four-valence average of Ge or Si. Indium (III) antimonide (IrSb), aluminium phosphide (AlP) and gallium arsenide are examples of Group 13-15 chemicals (GaAS). GaAs semiconductors have changed the design of electronic devices due to their fast reaction time.

Q10. What exactly is a semiconductor? Explain the two main types of semiconductors when they are doped with-

(a) an element of group 13,

(b) an element of group 15

A. Semiconductors are materials with conductivities that fall between those of metals (conductors) and insulators.

Both n-type and p-type semiconductors are widely used.

(a) An n-type semiconductor When a silicon crystal is doped with group-15 elements such as P, As, Sb or Bi, only four of the five valence electrons of each impurity atom participate in the formation of covalent bonds. The fifth electron conducts electricity almost completely free of charge. An n-type semiconductor is silicon that has been doped with elements from Group 15.

(b) B, Al, Ga, or other Impurities in silicon crystals form only three covalent bonds with the host atoms. The hole created by the absence of the fourth electron, t, causes the conductivity of the crystal to increase. P-type semiconductors are silicon doped with a group-13 element.

CBSE Class 12 Chemistry Important Questions

Class 12 Chemistry Chapter 1 ‘Solid State’ is significant because it contains questions of one, two or three marks. This chapter is relatively simple and can be understood if the basics are clear. The chapter ‘Solid State’ discusses various solid structures formed by different particle arrangements. It describes the properties and characteristics of various types of solids. Students must pay close attention to the definitions, diagrams and numerical values explained in the chapter.

FAQs (Frequently Asked Questions)

1. What are the different categories of crystalline solids?

The following are the different types of crystalline solids:

  • Molecular Solids- These solids are insulators, are soft, and have a lower density. For example- Sugar.
  • Metallic solids have high boiling and melting points, as well as metallic and thermal conductivity. For example- All alloys and metals.
  • Ionic Solids have extremely high boiling and melting points. For example- NaCl, six Cl- ions surround the Na+ ion.
  • Network/Covalent Solids- Covalent bonds hold the atoms of these solids together. They are typically bad conductors. For example- Graphite.

2. What are the types of solids based on their electrical and magnetic properties?

Based on their electrical conductivity, solids are classified into three types:

  1. Conductors,
  2. Insulators and
  3. Semiconductors.

Based on their magnetic properties, solids are classified into five types:

  1. Diamagnetic,
  2. Paramagnetic,
  3. Ferromagnetic,
  4. Antiferromagnetic and
  5. Ferrimagnetic materials.

3. Explain Schottky defect.

It is a stoichiometric flaw caused by the absence of an equal number of anions and cations from the lattice. This flaw is frequently observed in ionic compounds with a high coordination number. The sizes of anions and cations are similar. Because of this stoichiometric defect, the density of the crystal decreases. Because of its smaller size, it also conducts electricity. For example, potassium chloride, sodium chloride, potassium bromide and others.

4. Explain the Frenkel defect.

The Frenkel defect is a stoichiometric interstitial defect that occurs when some ions occupy lattice interstitial sites. These ions occupy new spaces after leaving the lattice sites. This flaw is frequently observed in ionic crystals where the cation is smaller than the anion. This flaw has no effect on the density of the lattice. Electrical conductivity increases to a small extent. The Frenkel defect has no effect on the overall chemical composition of the crystal. For example, Silver bromide, zinc sulphide, etc.