Course Content
CHAPTER 1: SOME BASIC CONCEPTS OF CHEMISTRY
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Introduction of Chemistry
14:32
Matter || Pure Substance || Properties of Matter
Quantitative property || The International System of Units (SI) || Prefixes used in SI System || Scientific Notation
Precision & Accuracy || Significant figures || Dimensional Analysis
Law of Chemical Combination
Dalton’s Atomic Theory || Atomic Mass || Average Atomic Mass || Molecular Mass
Mole Concept and Molar Masses || Percentage Composition || Empirical Formula for Molecular formula
Stoichiometry || Limiting Reagent
Reactions in Solution – Mass per cent or weight percent || Mole fraction || Molarity || Molality
NCERT Solutions for Class 11 Chemistry Chapter 1 Some basic Concepts of Chemistry
CBSE Class 11 Chemistry Chapter-1 Important Questions
Chemistry Question Bank || NEET || JEE || AIIMS
Class 11th Chemistry Chapter 1 Quiz Test For Students
01:30:00
CHAPTER 2: STRUCTURE OF ATOM
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INTRODUCTION || DISCOVERY OF ELECTRON
30:35
DISCOVERY OF PROTON || DISCOVERY OF NEUTRON || ATOMIC MODELS OF ATOM
ISOTOPES || ISOBARS || ISOTONES || ISOELECTRONIC
DUAL NATURE OF LIGHT: DEVELOPMENT LEADING TO BOHR’S MODEL || Black body radiation and Photoelectric effect
Planck’s quantum theory || BOHR’S THEORY
EXPLANATION OF HYDROGEN SPECTRA || LIMITATIONS OF BOHR MODEL OF AN ATOM || DUAL NATURE OF PARTICLE || QUANTUM MECHANICS || Pauli’s exclusion Principle
NCERT Solutions for Class 11 Chemistry Chapter 2 Structure of Atom
CHAPTER 3: CLASSIFICATION OF ELEMENTS
Section Name Topic Name 3 Classification of Elements and Periodicity in Properties 3.1 Why do we Need to Classify Elements ? 3.2 Genesis of Periodic Classification 3.3 Modern Periodic Law and the present form of the Periodic Table 3.4 Nomenclature of Elements with Atomic Numbers > 100 3.5 Electronic Configurations of Elements and the Periodic Table 3.6 Electronic Configurations and Types of Elements: s-, p-, d-, f – Blocks 3.7 Periodic Trends in Properties of Elements
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Introduction || Doberneiner’s Triads
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Newland’s Law of Octave || Limitations of Newlands’ law of octaves
Mendeléev’s periodic table || Achievements of Mendeléev’s periodic table || Limitation of Mendeleev’s classification
The Modern Periodic Table || Position of Element in Modern Periodic Table || Trends in the modern periodic table
NCERT Solutions for Class 11 Chemistry Chapter 3 Classification of Elements and Periodicity in Properties
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CHAPTER 4: CHEMICAL BONDING AND MOLECULAR STRUCTURE
4 Chemical Bonding and Molecular Structure 4.1 Kössel-Lewis Approach to Chemical Bonding 4.2 Ionic or Electrovalent Bond 4.3 Bond Parameters 4.4 The Valence Shell Election Pair Repulsion (VSEPR) Theory 4.5 Valence Bond Theory 4.6 Hybridisation 4.7 Molecular Orbital Theory 4.8 Bonding in Some Homonuclear Diatomic Molecules 4.9 Hydrogen Bonding
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Introduction || Kossel and Lewis Approach
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Types of chemical bond || Factors affecting the formation of ionic bond || General properties of ionic compounds
COVALENT BOND || COORDINATE BOND
Bond parameters : Bond Length , Bond Angle, Bond Enthalpy, Bond Order || Resonance
Polarity & Dipole moment || Ionic Percentage || Polarization
VSEPR THEORY || Hybridization || Valence bond theory || Overlapping: sigma and pi bond || Molecular orbital theory
Hydrogen bonding || Hydrogen bonding in ice and water
NCERT Solutions for Class 11 Chemistry Chapter 4 Chemical Bonding and Molecular Structure
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CHAPTER 5: STATE OF MATTER
Section Name Topic Name 5 States of Matter 5.1 Intermolecular Forces 5.2 Thermal Energy 5.3 Intermolecular Forces vs Thermal Interactions 5.4 The Gaseous State 5.5 The Gas Laws 5.6 Ideal Gas Equation 5.7 Kinetic Energy and Molecular Speeds 5.8 Kinetic Molecular Theory of Gases 5.9 Behaviour of Real Gases: Deviation from Ideal Gas Behaviour 5.10 Liquefaction of Gases 5.11 Liquid State
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Introduction || State of Matter
27:52
Intermolecular Forces || Dispersion Forces or London Forces
Dipole – Dipole Forces || Dipole – Induced Dipole Force || Hydrogen Bond || Thermal Energy
Intermolecular Forces Vs Thermal Interations || Boyle’s Law || Charles’ Law || Gay Lussac’s Law
Avogadro Law || Ideal Gas Equation || Density and Molar Mass of a Gaseous Substance
Dalton’s Law of Partial Pressure || Partial pressure in terms of mole fraction || Kinetic molecular theory of gases || Behaviour of real gases: deviation from ideal gas behaviour || Surface Tension
Viscosity
NCERT Solutions for Class 11 Chemistry Chapter 5 States of Matter
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State of Matter Question For NEET || JEE || AIIMS
CHAPTER 6: THERMODYNAMICS
Section Name Topic Name 6 Thermodynamics 6.1 Thermodynamic Terms 6.2 Applications 6.3 Measurement of ∆U and ∆H: Calorimetry 6.4 Enthalpy Change, ∆rH of a Reaction – Reaction Enthalpy 6.5 Enthalpies for Different Types of Reactions 6.6 Spontaneity 6.7 Gibbs Energy Change and Equilibrium
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Thermodynamics of Thermodynamics || Universe || System || Surrounding || types of systems || Internal Energy
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1st Law of Thermodynamics || Enthalpy || Heat capacity || Types of molar heat capacities || Relation between Cp &Cv || Calorimeter
Enthalpies of Reaction || Enthalpy of Combustion || Calorific value || Hess’s law of heat summation || Other type of enthalpies || Born- Haber cycle || Enthalpies of phase transition || Bond enthalpy || Limitation of 1st law of thermodynamics
Entropy || How s & q related? || How S&T related? || Second law of thermodynamics || Standard molar entropy || Gibbs free energy || Third law of thermodynamics
NCERT Solutions for Class 11 Chemistry Chapter 6 Thermodynamics
NCERT Solutions for Class 11 Chemistry Chapter 6 Very Short Answer Type Questions
NCERT Solutions for Class 11 Chemistry Chapter 6 Short Answer Type Questions
NCERT Solutions for Class 11 Chemistry Chapter 6 Long Answer Type Questions
CHAPTER 7: EQUILIBRIUM
Section Name Topic Name 7 Equilibrium 7.1 Equilibrium in Physical Processes 7.2 Equilibrium in Chemical Processes – Dynamic Equilibrium 7.3 Law of Chemical Equilibrium and Equilibrium Constant 7.4 Homogeneous Equilibria 7.5 Heterogeneous Equilibria 7.6 Applications of Equilibrium Constants 7.7 Relationship between Equilibrium Constant K, Reaction Quotient Q and Gibbs Energy G 7.8 Factors Affecting Equilibria 7.9 Ionic Equilibrium in Solution 7.10 Acids, Bases and Salts 7.11 Ionization of Acids and Bases 7.12 Buffer Solutions 7.13 Solubility Equilibria of Sparingly Soluble Salts
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Introduction || Types of equilibrium || Boiling point || Equilibrium involving dissolution of solids || General characteristics of physical equilibrium || Equilibrium Involving in Chemical Process
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Law of mass action || Characteristics of Equilibrium constant (k) || Characteristics of chemical equilibrium || Effect of temperature on K
Chemical equilibrium || Characteristics of K || Application of Equilibrium constant || Factors affecting state of equilibrium “Le Chartlier’s principle || Substances: electrolytes and non electrolytes
Acids, bases and salts || 2nd Concept: Bronsted Lowry concept || Conjugate acid –base concept || 3rd concept: Lewis concept || Expressing Hydrogen ion concentration: pH scale || Calculation of PH Value
Protic and non- Protic acids || Hydrolysis of salt || Different kind of salts || Buffer solution || Solubility product ||
NCERT Solutions for Class 11 Chemistry Chapter 7 Equilibrium
NCERT Solutions for Class 11 Chemistry Chapter 7 Very Short Answer Type Questions
CHAPTER 8: REDOX REACTIONS
Section Name Topic Name 8 Redox Reactions 8.1 Classical Idea of Redox Reactions-Oxidation and Reduction Reactions 8.2 Redox Reactions in Terms of Electron Transfer Reactions 8.3 Oxidation Number 8.4 Redox Reactions and Electrode Processes
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Introduction || Oxidation and Reduction || oxidation number || Redox reaction in terms of oxidation number
Balancing of Redox reactions || Types of Redox reactions
Redox couple || Electrochemical cell || Functions of salt bridge || Representation of the cell || Electrode potential || Electromotive force || Electromotive force || Electrochemical series || Redox reaction as the basis for Titrations
NCERT Solutions for Class 11 Chemistry Chapter 8 Redox Reactions
NCERT Solutions for Class 11 Chemistry Chapter 8 Very Short Answer Type Questions
NCERT Solutions for Class 11 Chemistry Chapter 8 Short Answer Type Questions
CHAPTER 9: HYDROGEN
Section Name Topic Name 9 Hydrogen 9.1 Position of Hydrogen in the Periodic Table 9.2 Dihydrogen, H2 9.3 Preparation of Dihydrogen, H2 9.4 Properties of Dihydrogen 9.5 Hydrides 9.6 Water 9.7 Hydrogen Peroxide (H2 O2) 9.8 Heavy Water,D2O 9.9 Dihydrogen as a Fuel
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Introduction || Characteristics of Hydrogen || Difference with alkali metals || Similarities with Halogens || Differences with Halogen || Dihydrogen
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Physical properties of H2 || Chemical Properties || Uses of H2
Hydrides || Covalent or molecular hydrides || Metallic  hydrides
Water || Physical properties || Chemical properties || Hardness of water  || Methods to remove hardness
Hydrogen peroxide || Physical Properties || Chemical Properties || Uses of Hydrogen peroxide
Heavy water || Physical properties || Chemical Properties
NCERT Solutions for Class 11 Chemistry Chapter 9 Hydrogen
NCERT Solutions for Class 11 Chemistry Chapter 9 Very Short , Short and Long Answer Type Questions
CHAPTER 10: S-BLOCK ELEMENTS
Section Name Topic Name 10 The s-Block Elements 10.1 Group 1 Elements: Alkali Metals 10.2 General Characteristics of the Compounds of the Alkali Metals 10.3 Anomalous Properties of Lithium 10.4 Some Important Compounds of Sodium 10.5 Biological Importance of Sodium and Potassium 10.6 Group 2 Elements : Alkaline Earth Metals 10.7 General Characteristics of Compounds of the Alkaline Earth Metals 10.8 Anomalous Behaviour of Beryllium 10.9 Some Important Compounds of Calcium 10.10 Biological Importance of Magnesium and Calcium
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Introduction || Diagonal Relationship || Atomic and Ionic Radii of alkali metals
25:32
Ionization Enthalpy and Hydration Enthalpy of alkali metals || Physical properties of alkali metals || Chemical Properties of alkali metals || Anomalous properties of lithium || Washing Soda
Preparation of washing soda by solvay’s process || Sodium Chloride || Caustic Soda || Baking Soda || Electronic Configuration of alkaline earth metal || Atomic and Ionic Radii of alkaline earth metal
Ionization Enthalpy of alkaline earth metal || Hydration Enthalpy of alkaline earth metal || Physical Properties of alkaline earth metal || Chemical Properties of alkaline earth metal
Quick Lime || Slaked Lime || Calcium Carbonate (CaCO3) || Plaster of Paris || Cement || Uses of s-block elements
NCERT Solutions for Class 11 Chemistry Chapter 10 The s-Block Elements
NCERT Solutions for Class 11 Chemistry Chapter 10 Very Short, Short & Long Answer Type Questions
CHAPTER 11: P-BLOCK ELEMENTS
Section Name Topic Name 11 The p-Block Elements 11.1 Group 13 Elements: The Boron Family 11.2 Important Trends and Anomalous Properties of Boron 11.3 Some Important Compounds of Boron 11.4 Uses of Boron and Aluminium and their Compounds 11.5 Group 14 Elements: The Carbon Family 11.6 Important Trends and Anomalous Behaviour of Carbon 11.7 Allotropes of Carbon 11.8 Some Important Compounds of Carbon and Silicon
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Introduction of p- block || Inert pair effect || Group 13 Elements
Chemical properties of group 13 || Important trends || Uses of Boron || Uses of Aluminum || Borax || PROPERTIES OF BORAX || Uses of Borax
Introduction of Group – 14 || Physical Properties of group 14 || Chemical properties of group 14 || Structure of CCl4 || Allotropes of carbon || Properties and Uses of diamond and graphite || Types of Charcoal || Uses of Carbon, Germanium, Lead, & Tin.
Carbon monoxide (CO) || Carbon dioxide (CO2) || Silicon dioxide (SiO2) || Crystalline form of silica || Structure of Silicon dioxide || Silicones || Silicates || Zeolites
NCERT Solutions for Class 11 Chemistry Chapter 11 The p-Block Elements
NCERT Solutions for Class 11 Chemistry Chapter 11 Very Short, Short & Long Answer Type Questions
CHAPTER 12: CHARACTERIZATION OF ORGANIC COMPOUND
Section Name Topic Name 12 Organic Chemistry – Some Basic Principles and Techniques 12.1 General Introduction 12.2 Tetravalence of Carbon: Shapes of Organic Compounds 12.3 Structural Representations of Organic Compounds 12.4 Classification of Organic Compounds 12.5 Nomenclature of Organic Compounds 12.6 Isomerism 12.7 Fundamental Concepts in Organic Reaction Mechanism 12.8 Methods of Purification of Organic Compounds 12.9 Qualitative Analysis of Organic Compounds 12.10 Quantitative Analysis
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Introduction || COMPOUNDS || Friedrich Wohler || IMPORTANT FEATURE OF π BONDS  || Branches of Organic Compounds || Functional Group
19:51
Homologous series || IUPAC system || Different Type of Organic Compounds ||  Alkyl halides
IUPAC and Common names of compounds || RULES FOR IUPAC || In case of double & triple bond
RULES FOR NAMING ORGANIC COMPOUND WITH FUNCTIONAL GROUP || PREFIX USED FOR SECONDARY FUNCTIONAL GROUP || NOMANCLATURE OF AROMATIC COMPOUNDS
ISOMERISM || The structural isomerism type || The different types of stereoisomerism || CONFORMATIONAL ISOMERISM
ELECTRON DISPLACEMENT IN COVALENT BONDS || HYPER CONJUGATION || Fundamental concepts of organic reactions || REACTION INTERMEDIATES
Types of Carbocations || Carboanion || Types of Carboanions ||  Attacking agents
Types of organic reactions || Addition Reaction || Elimination reaction
Methods of purification of organic compounds || Crystallisation || Distillation || Fractional distillation || Distillation under reduced pressure || Steam distillation
Differential extraction || Chromatography || Adsorption chromatography || Column chromatography || Thin layer chromatography || Position chromatography
Detection of carbon and hydrogen || Detection of other elements || Test for Nitrogen || Test for Sulphur || Test for halogens ||  Test for phosphorous || Quantitative analysis || Dumas method || Kjeldahl’s method
NCERT Solutions for Class 11th Chemistry Chapter 12 Organic Chemistry Some Basic Principles and Techniques
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CHAPTER 13: HYDROCARBON
Section Name Topic Name 13 Hydrocarbons 13.1 Classification 13.2 Alkanes 13.3 Alkenes 13.4 Alkynes 13.5 Aromatic Hydrocarbon 13.6 Carcinogenicity and Toxicity
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Introduction || Classification of hydrocarbons || Aromatic || Alkanes || Introduction of alkanes || Isomerism is alkanes
20:34
Classification of Alkanes || Preparation of alkanes
Physical Properties of alkanes || Chemical properties of alkanes
Conformational Isomerism || Torsional strain
Alkenes || ISOMERISM || Stereoisomerism || Stability of Alkenes || Preparation  of Alkenes ||  Physical Properties Of alkenes
Chemical properties of alkenes
Alkynes ||  Structure of ethyne || Isomerism || Preparation of Alkynes || Physical properties of alkynes || Chemical properties of alkynes
Aromatic Compounds || Nomenclature || Isomerism || Stability and structure of benzene || Huckle rule of Aromatic compounds || Preparation of Benzene || Physical properties of benzene || Chemical properties of benzene
NCERT Solutions for Class 11 Chemistry Chapter 13 Hydrocarbons
NCERT Solutions for Class 11 Chemistry Chapter 13 Very Short , Short and Long Answer Type Questions
CHAPTER 14: ENVIRONMENTAL CHEMISTRY
Section Name Topic Name 14 Environmental Chemistry 14.1 Environmental Pollution 14.2 Atmospheric Pollution 14.3 Water Pollution 14.4 Soil Pollution 14.5 Industrial Waste 14.6 Strategies to control Environmental Pollution 14.7 Green Chemistry
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Introduction || Atmosphere || Environmental chemistry || Environmental pollution || Atmospheric pollution || causes of pollution
Types of pollutants || Primary pollutant || Secondary pollutant || Biodegradable || Non-biodegradable
Types of pollution || Air pollution || Water pollution || Soil pollution
Green House Effect || Global warming || Acid rain || Hydrocarbons || Chlorofluorocarbons
Ozone || Ozone hole || Montreal protocol || Particulate pollutants
Smog and Photochemical smog
Water pollution
Soil pollution || Management of industrial waste
Green chemistry
NCERT Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry
NCERT Solutions for Class 11 Chemistry Chapter 14 Very Short, Short & Long Answer Type Questions
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About Lesson

NCERT Solutions for Class 11 Chemistry Chapter 10 Very Short Answer Type Questions

Question 1. Name the alkali metal which shows diagonal relationship with magnesium?
Answer:  Li.

Question 2. Why alkali and alkaline earth metals cannot be obtained by chemical reduction method?
Answer:  Because alkali and alkaline earth metals are themselves stronger reducing agents than the majority of other reducing agents.

Question 3. Name the compounds used for the manufacture of washing soda by Solvay process.
Answer: NaCl, CaCO3 and NH3.

Question 4. Which electrolyte is used to obtain sodium in Castner’s process?
Answer: Fused NaOH.

Question 5. What happens when crystals of washing soda are exposed to air?
Answer: Monohydrate (Na2CO3– H2O) is formed as a result of efflorescence.

Question 6. Name the alkaline earth metals whose salt do not impart colour to a non-luminous flame.
Answer:  Beryllium does not impart colour to a non-luminous flame.

Question 7. What is dead burnt plaster?
Answer: It is anhydrous calcium sulphate (CaSO4).

Question 8. What is Quick lime? What happens when it is added to water?
Answer:  CaO is quick lime. When it is added to water, Ca(OH)2 is formed.

Question 9. Arrange the following in the increasing order of solubility in water.
 MgCl2, CaCl2, SrCl2, BaCl2
Answer: BaCl2 < SrCl2 < CaCl2 <MgCl2

Question 10. Give the chemical formula of Epsom salt.
Answer: MgSO4,7H2O

Question 11. How would you prepare sodium silicate from silica?
Answer:

Question 12. What happens when sodium metal is heated in free supply of air?
Answer:  Sodium peroxide is formed.
2Na + O2 ——-> Na2O2

Question 13. What is the general name for elements of group 1 ?
Answer:  Alkali metals.

Question 14. Why are alkali metals soft?
Answer: Since the atoms of alkali metals have bigger kernels and smaller number of valence electrons, the metallic bonds in them are very weak and hence are soft.

Question 15. What do you mean by diagonal relationship in periodic table?
Answer: The resemblance of the first element of second period with diagonally situated element of neighbouring element is called diagonal relationship.

Question 16. Why is BeCl2 soluble in organic solvent?
Answer: Since BeCl2 is a covalent compound it is soluble in organic solvent.

Question 17. Why do alkali metals give characteristic flame colouration?
Answer: Alkali metals due to low ionization energy absorb energy from visible region to radiate complementary colour.

Question 18. Why is the solution of alkali metals in liquid ammonia conducting in nature?
Answer: Due to ammoniated electrons and cations.

Question 19. Which is more basic NaOH or Mg(OH)2?
Answer: NaOH is more basic.

Question 20. Which alkaline earth metals do not impart colour to the flame?
Answer:  Be and Mg.

Question  21. What is soda ash?
Answer: Soda ash is anhydrous sodium carbonate (Na2CO3).

NCERT Solutions for Class 11 Chemistry Chapter 10 Short Answer Type Questions

Question 1. Why are alkali metals always univalent? Which alkali metal ion forms largest hydrated ion in aqueous solution?
Answer: They are always univalent because after losing one electron, they aquire nearest inert gas configuration.Li+ forms largest hydrated cations because it has the highest hydration energy.

Question 2. What is the effect of heat on the following compounds (Give equations for the reactions)? (i) CaC03 (ii) CaSO4 2H2O

Question 3. Explain the following:
(a) Lithium iodide is more covalent than lithium fluoride.
(b) Lattice enthalpy of LiF is maximum among all the alkali metal halides.
Answer: (a) According to Fazan’s rule, Li+ ion can polarise  l– ion more than the F– ion due to bigger size of the anion. Thus Lil– has more covalent character than LiF.
(b) Smaller the size (internuclear distance), more is the value of Lattice enthalpy since internuclear distance is expected to be least in the LiF.

Question 4. Write the chemical formula of the following compounds.
(i) Chile salt petre (ii) Marble (iii) Brine
Answer:(i) NaNO3 (ii) CaCO3 (iii) NaCl.

Question 5. Explain the following:
(a) Why Cs is considered as the most electropositive element?
(b) Lithium cannot be used in making photoelectric cells.
(c) Lithium does not form alums.
Answer: (a) Due to its lowest ionization energy, Cs is considered as the most electropositive element.
(b) Lithium cannot be used in making photoelectric cells because out of all the alkali metals it has highest ionization energy and thus cannot emit electrons when exposed to light.
(c) Due to small size, lithium does not form alums.

Question 6. (a) What makes lithium to show properties uncommon to the rest of the alkali metals?
(b) When is a cation highly polarising? Which alkali metal cation has the highest polarising power?
Answer: (a) The unusual properties of lithium as compared to other alkali metals is due to its exceptionally small size of atom and its ion and its high polarising power.
(b) A cation is highly polarising if its charge/ size ratio is very high.
Li+ ion has the highest polarising power.

Question 7. Why are ionic hydrides of only alkali metals and alkaline earth metals are known? Give two examples.
Answer: Alkali metals and alkaline earth metals are most electropositive due to low ionization ethalpy therefore they form ionic hydrides, e.g. NaH, KH and CaH2

Question  8. Why does the solution of alkali metals becomes blue in liquid ammonia? Give the chemical equation also.
Answer: The blue colour of the solution is due to ammoniated electron which absorbs energy in the visible region of light and imparts blue colour.
Na (am) + e- (am) + NH3(l) ——–> NaNH2(am) + —1/2 H2(g)

Question 9. Give the important uses of the following compounds.
(i) NaHCO3 (ii) NaOH
Answer:

(i) Uses of NaHCO3

  • It is used in fire extinguisher.
  • It is mild antiseptic for skin infections.
  • It is used as antacid.

(ii)Uses of NaOH

  • It is used in soap industry.
  • It is used in textile industry.
  • It is used as reagent in laboratory.
  • It is used in absorbing poisonous gases.

Question 10. What is the mixture of CaC2 and N2 called? How is it prepared?
Answer:  It is called Nitrolime.
It is prepared by heating CaC2 with N2 at high temperature.
CaC2 + N2 ——–> CaCN2 + C

NCERT Solutions for Class 11 Chemistry Chapter 10 Long Answer Type Questions

Question 1. (a) Compare four properties of alkali metals and alkaline earth metals.
(b) What happens when alkali metals are dissolved in ammonia?
(c) MgCl2 is electrolysed.
Answer: (a)

Question 2. State as to why
(a) Alkali metals show only +1 oxidation state. (b) Na and K impart colour to the flame but Mg does not.(c) Lithium on being heated in air mainly forms the monoxide and not the peroxide.(d) Li is the best reducing agent in aqueous solution.
Answer:  (a) Alkali metals have low ionization enthalpies.
They have a strong tendency to lose 1 electron to form unipositive ions. Thus they show an oxidation state of +1 and are strongly electropositive.
(b) Valence electrons of alkali metals like Na and K easily absorb energy from the
flame and are excited to higher energy levels. When these electrons return to the ground state, the energy is emitted in the form of light.
Magnesium atom has small size so electrons are strongly bound to the nucleus. [ Thus they need large amount of energy for excitation of electrons to higher
energy levels which is not possible in bunsen flame.
(c)Due to the small size of Li+ it has a strong positive field which attracts the negative charge so strongly that it does not permit the oxide ion, 02- to combine with another oxygen atom to form peroxide ion.
(d)Since, among alkali metals, lithium has the most negative electrode potential (E° = -3.04 V) so, it is the strongest reducing agent in the aqueous solution.

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