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Introduction

All of the body’s cells require energy to support various metabolic processes, thus every living thing engages in cellular respiration to release energy, which is then stored in the form of ATP. After ingestion, food is transported into the stomach via the oesophagus, where stomach acids and enzymes break it down into several smaller bits, including glucose. Since glucose is the most prevalent monosaccharide and the first substrate for the metabolism of carbohydrates, where it is broken down to release energy, glucose and ATP are the molecules that carry the energy.

Definition of Cellular Respiration

All plant and animal cells produce energy through a process called cellular respiration (excluding RBCs). Food glucose is broken down into carbon dioxide, water, and energy with or without oxygen throughout this process. As a result, it liberates ATP and releases carbon dioxide as a waste product (adenosine triphosphate).

Difference between Respiration and Breathing

Respiration	Breathing
Respiration is the physiological process of breathing in and breathing out. Energy is released from cells during the chemical breakdown of food-derived glucose.	Breathing is the movement of oxygen into the body from the outside environment and the release of carbon dioxide from the lungs into the outside environment.
It is categorised into cellular respiration and physiological respiration.	Since breathing is a form of respiration, it is often referred to as physiological respiration.
In cells, and notably in cellular organelles like the cytosol and mitochondria, cellular respiration takes place.	It takes place in the lungs.
There is the involvement of enzymes.	There is no involvement of enzymes.
It produces ATP that is converted into energy.	It does not produce energy.

Glycolysis

• One glucose molecule is broken down into two pyruvate molecules in this process, which also results in the creation of ATP. 
• Every cell in the body contains it in the cytoplasm. Hexokinase enzyme converts glucose to glucose-6-phosphate.
• By using phospho-hexose isomerase, which are isomers of one another, glucose 6-phosphate is converted to fructose 6-phosphate. 
• By phosphorylating fructose 6-phosphate, phosphofructokinase catalyzes the irreversible conversion of fructose 6-phosphate to fructose 1,6-bisphosphate.
• Aldolase catalyzes the breakdown of fructose 1,6 bisphosphate into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate.
• The reversible interconversion of glyceraldehyde 3-phosphate and dihydroxyacetone phosphate is carried out by phosphotriose isomerase.
• Glyceraldehyde 3-phosphate is converted to 1,3-bisphosphoglycerate by glyceraldehyde 3-phosphate dehydrogenase. 
• In this stage, \(NA{D^ + }\) is converted to \(NAD{H^ + }\) and \({H^ + }\), which adds a phosphate group to glyceraldehyde 3-phosphate. With the creation of ATP, the enzyme phosphoglycerate kinase converts 1,3-bisphosphoglycerate into 3-phosphoglycerate.
• Phosphoglycerate mutase converts 3-phosphoglycerate into 2-phosphoglycerate, and these two substances are isomers. 
• Enolase transforms 2-phosphoglycerate into the highly energetic molecule phosphoenolpyruvate once water is removed. 
• In the presence of pyruvate kinase, phosphoenol pyruvate is transformed into pyruvate along with the creation of ATP.       
•  

Generation of ATP: Two pyruvates, two NADH, and two ATP molecules are the final products of glycolysis. Due to the conversion of glucose into two pyruvates, 8 ATP molecules are produced.

Krebs Cycle

Acetyl CoA is converted into carbon dioxide and water by some chemical processes called Krebs cycle.

• Pyruvate is converted to acetyl CoA through oxidative decarboxylation by pyruvate dehydrogenase. 
• The elimination of carboxylate groups to create carbon dioxide is known as oxidative decarboxylation. Acetyl CoA and oxaloacetate are condensed by citrate synthase. 
• Aconitase converts citrate into isocitrate.
• Isocitrate dehydrogenase uses oxidative decarboxylation to change the isocitrate to oxalosuccinate, which is then transformed into -ketoglutarate. 
• By removing the carboxylate group from ketoglutarate and generating carbon dioxide, the enzyme ketoglutarate dehydrogenase transforms ketoglutarate to succinyl CoA. 
• Succinate thiokinase causes succinyl CoA to be converted to succinate. A phosphorylated group is added to GDP to create GTP, which is then converted into ATP by a protein called nucleoside diphosphate kinase. 
• By catalysing the conversion of succinate to fumarate and producing \(FAD{H_2}\), succinate dehydrogenase.
• By including water, fumarase catalyses the conversion of fumarate to malate.
• Malate dehydrogenase converts malate to oxaloacetate and generates NADH in the process. 
• The cycle is maintained by mixing the oxaloacetate with more acetyl CoA molecules.
• 

Generation of ATP: In the Krebs cycle, 12 ATP is produced as a result of the production of 2 \(C{O_2}\), 3 NADH, and 1\(FAD{H_2}\).

Electron Transport Chain or Terminal Oxidation or Oxidative Phosphorylation

The proton gradient created by the electron transport chain (ETC), a chain of proteins that transports electrons through the mitochondrial membrane, powers ATP generation. A series of ETC enzyme complexes: 

• NADH-ubiquinone reductase – Complex I
• Succinate CoQ reductase – Complex II
• Ubiquinone-cytochrome c oxidoreductase – Complex III
• Cytochrome oxidase – Complex IV 
• ATP synthase – Complex V 

Through electron carriers such as flavoproteins, cytochromes, coenzyme Q, nicotinamide nucleotides, and iron-sulfur proteins, these catalyze the transport of electrons.

Since energy is lost during the passage of electrons through ETC, the ATP synthase complex uses the energy to produce ATP from ADP, a procedure known as oxidative phosphorylation. 32 ATP molecules are generated during oxidative phosphorylation and ETC.

Differences between Glycolysis and Krebs Cycle

Glycolysis	Krebs cycle
It involves both aerobic and anaerobic respiration.	It involves only aerobic respiration.
The substrate substance is glucose.	The substrate material is acetylAcetyl CoA.
Glycolysis takes place in the cytoplasm.	The KrebsKrebs cycle takes place in the mitochondria.
It consumes two molecules of ATP.	It does not consume ATP.
Carbon dioxide is released in glycolysis.	Carbon dioxide is not released in the Krebs cycle.
It is a linear enzymatic reaction.	It is a non-linear pathway.
It occurs in both eukaryotes and prokaryotes.	It occurs in eukaryotes.

Difference between Aerobic and Anaerobic Respiration

Summary 

All plant and animal cells produce energy through a process called cellular respiration. Due to the conversion of glucose into two pyruvates, 8 ATP molecules are produced in glycolysis. In the Krebs cycle, 12 ATP is produced as a result of the production of 2 \(C{O_2}\), 3 NADH, and 1 \(FAD{H_2}\). 32 ATP molecules are generated during oxidative phosphorylation and ETC.

Frequently Asked Questions

1.How do electron carriers function?,
Ans. The metabolite is present at one end and oxygen is at the other end, therefore the electrons are carried by a series of proteins.

2. What are the processes in the conversion of glucose to pyruvate that require energy?
Ans. By using enzymes in intermediary processes, glyceraldehyde 3-phosphate and dihydroxyacetone phosphate are produced from glucose. These processes call for energy.

3. What is oxidative phosphorylation?
Ans. Oxidative phosphorylation, which takes place in the mitochondria, is the addition of the phosphate group through reactions that use the energy produced when ATP is made from ADP.

4. What is the importance of cellular respiration in living organisms?
Ans. Energy is released during cellular respiration, which activates a number of bodily processes. Therefore, ensuring the survival of living things is important.

Introduction

All science and technology are built on measurements. Every measurement is made by calculating an instrument which yields some ambiguity or doubt. This ambiguity is referred to as an error.  This measurement flaw can be described in two ways: 

1. Precision

Every measurement is dependent on the precision of the measuring tool and the skill of the person performing it. We won’t get the same result if we repeat a specific measurement because each result is susceptible to some experimental difficulty or inaccuracy. 

2. Accuracy

When getting measurements, it is critical to believe these measurements. Both values indicate the degree to which a measurement is close to a known or acceptable value.

Define Accuracy

It is defined as the ability to relate a physical quantity’s true value to a measurement. When these difficulties or inaccuracies are reduced, the measurement becomes more precise.

Define Precision

Precision is defined by the smallest count of measurement equipment. Precision is greatest when the count is the smallest. Precision is the amount of information conveyed in terms of its digits; it indicates the proximity of two or more measurements to one another. 

What are the differences between Accuracy and Precision?

Accuracy	Precision
The near value of a measurement to the true value of a physical quantity is defined as accuracy.	Precision is defined as the slightest count of the measuring instrument. Or closeness to the actual readings of the same quantity.
Accuracy can only be dependent on a single factor or quantity.	Whereas, the precision can be altered or dependent on multiple factors.
Accuracy is expressed in the terms of the errors.	The precision is expressed in the terms of the deviation.
The determination of accuracy is dependent on a single measurement.	The determination of precision is dependent on multiple measurements.
Accuracy is dependent on precision. When results are accurate, they are also precise.	There is no dependence on accuracy. The results can be precise without being accurate. This shows no dependence of accuracy on precision.

Summary

When experts consider error, they always think about accuracy and precision. It is defined as the ability to relate measurement to the true value of a physical quantity. Precision is defined as the measuring instrument’s smallest count. It is clear from the preceding explanation that the best scientific outcomes are only likely if they are both accurate and precise.

Frequently Asked Questions

1. According to one chocolate company, each bag of chocolate weighs 31.8 g. Jayant weighs two bags and discovers that they weigh 31.9 g and 32.3 g, respectively. How would Jayant describe the precision and accuracy of the first bag he measured?

Ans. The first bag’s claimed mass is correct. This is due to the fact that the brand specifies that each bag should contain 31.8 g, and the first bag did contain 31.8 gm. The claim for the first bag is not precise because the results are not identical.

2. How to determine Accuracy and Precision?

Ans. The accuracy of an experiment is calculated by the mean value of multiple measurements.

The precision of a set of measurements can be calculated by the standard deviation.

3. What is the relationship between accuracy, precision, and error?

Ans. The ability to relate the true value of a physical quantity to a measurement is defined as accuracy. When these difficulties or inaccuracies are reduced, the measurement becomes more precise. Precision is the ease with which a measurement can be replicated. Precision is defined by the measurement equipment’s smallest count. Precision is greatest when the count is the smallest. The precision of a set of values obtained by repeatedly measuring a quantity is defined as the closeness of the set of values obtained. As a result, more measurements will result in better precision, which will result in a smaller error, which will result in an improvement in accuracy.

Introduction

Chemical elements are the fundamental building blocks of chemistry, and everything around us is made up of elements. The periodic table is a tabular display of elements found in chemistry that are arranged by atomic number. A periodic table is an important tool for chemists, material scientists, and nanotechnologists because it provides so much information about the elements that it is easy to predict the physical and chemical properties of the elements. The periodic table demonstrates a fundamental but critical principle that the atomic number is responsible for chemical properties.

The periodic table contains how many elements?

The periodic table contains 118 elements organized in 7 rows and 18 columns. The rows (from left to right) are called ‘periods,’ and the columns (from top to bottom) are called ‘groups.’ All chemical elements have different physical and chemical properties, which change as you move in the periodic table. The arrangement is made so that the elements in the same column have similar properties. Surprisingly, only 94 of these 118 elements exist naturally.

118 Elements Name and Symbols and Atomic Numbers in Chemistry

Name of the Element	Symbol	Atomic Number
Hydrogen	H	1
Helium	He	2
Lithium	Li	3
Beryllium	Be	4
Boron	B	5
Carbon	C	6
Nitrogen	N	7
Oxygen	O	8
Fluorine	F	9
Neon	Ne	10
Sodium	Na	11
Magnesium	Mg	12
Aluminium	Al	13
Silicon	Si	14
Phosphorus	P	15
Sulphur	S	16
Chlorine	Cl	17
Argon	Ar	18
Potassium	K	19
Calcium	Ca	20
Scandium	Sc	21
Titanium	Ti	22
Vanadium	V	23
Chromium	Cr	24
Manganese	Mn	25
Iron	Fe	26
Cobalt	Co	27
Nickel	Ni	28
Copper	Cu	29
Zinc	Zn	30
Gallium	Ga	31
Germanium	Ge	32
Arsenic	As	33
Selenium	Se	34
Bromine	Br	35
Krypton	Kr	36
Rubidium	Rb	37
Strontium	Sr	38
Yttrium	Y	39
Zirconium	Zr	40
Niobium	Nb	41
Molybdenum	Mo	42
Technetium	Tc	43
Ruthenium	Ru	44
Rhodium	Rh	45
Palladium	Pd	46
Silver	Ag	47
Cadmium	Cd	48
Indium	In	49
Tin	Sn	50
Antimony	Sb	51
Tellurium	Te	52
Iodine	I	53
Xenon	Xe	54
Cesium	Cs	55
Barium	Ba	56
Lanthanum	La	57
Cerium	Ce	58
Praseodymium	Pr	59
Neodymium	Nd	60
Promethium	Pm	61
Samarium	Sm	62
Europium	Eu	63
Gadolinium	Gd	64
Terbium	Tb	65
Dysprosium	Dy	66
Holmium	Ho	67
Erbium	Er	68
Thulium	Tm	69
Ytterbium	Yb	70
Lutetium	Lu	71
Hafnium	Hf	72
Tantalum	Ta	73
Tungsten	W	74
Rhenium	Re	75
Osmium	Os	76
Iridium	Ir	77
Platinum	Pt	78
Gold	Au	79
Mercury	Hg	80
Thallium	Tl	81
Lead	Pb	82
Bismuth	Bi	83
Polonium	Po	84
Astatine	At	85
Radon	Rn	86
Francium	Fr	87
Radium	Ra	88
Actinium	Ac	89
Thorium	Th	90
Protactinium	Pa	91
Uranium	U	92
Neptunium	Np	93
Plutonium	Pu	94
Americium	Am	95
Curium	Cm	96
Berkelium	Bk	97
Californium	Cf	98
Einsteinium	Es	99
Fermium	Fm	100
Mendelevium	Md	101
Nobelium	No	102
Lawrencium	Lr	103
Rutherfordium	Rf	104
Dubnium	Db	105
Seaborgium	Sg	106
Bohrium	Bh	107
Hassium	Hs	108
Meitnerium	Mt	109
Darmstadtium	Ds	110
Roentgenium	Rg	111
Copernicium	Cn	112
Nihonium	Nh	113
Flerovium	Fl	114
Moscovium	Mc	115
Livermorium	Lv	116
Tennessine	Ts	117
Oganesson	Og	118

The characteristics of the Periodic table

1. Electronegativity

2. Ionization Energy

3. Electron Affinity

4. Atomic Radius

Summary

To date, mankind has discovered 118 elements. Only 94 of these occur naturally. These elements are represented in the periodic table, which has seven rows and eighteen columns. Columns represent groups, and rows represent periods. All elements are members of similar groups with similar chemical properties. The chemical properties of elements are determined by their atomic number. The number of protons in the atom determines the atomic number. This number also indicates the number of electrons in the atom. The chemical properties of an element are determined by the electrons in the valence cells.

Frequently Asked Questions

1. Why do elements in the same group share physical and chemical properties?

Ans. The physical and chemical properties of elements depend on the number of valence electrons. Elements present in the same group have the same number of valence electrons. Therefore, elements present in the same group have similar physical and chemical properties.

2. Why are noble gases also called inert gases?

Ans. Noble gases are also known as inert gases because their electron configuration is the most stable. Because the valence shells are completely filled, they cannot lose or gain electrons.

3. Why ionization energy is always positive?

Ans. Electrons in an atom are bounded by forces of attraction from the nucleus. And we know the electron will be attracted to the nucleus due to the charge difference. This means the energy that is provided to take out an electron from its shell. This is why the ionization energy is always positive.

Introduction

The most important class of compounds in chemistry are acids and bases. Acids and bases are essential to practically every natural system, including human survival and the functioning of rocks and oceans. You must have come across acid and bases when you tasted lemon or washed your hands with soaps. Acids are sour and can be dangerously corrosive; bases are slippery and can be corrosive as well. In science, compounds are typically categorized as bases, acids, or neutral. The pH scale is used to determine how strong an acid or base is.

Acids

1. Acids release hydrogen ions or a proton when combined with water.

2. They exhibit a pH below 7 and turn blue litmus red. 

3. Arrhenius state that “those substances which give hydrogen ions \({H^ + }\) in aqueous solution” are known acids.

\[HA{\rm{ }} + {\rm{ }}{H_2}O{\rm{ }} \to {\rm{ }}{A^ – } + {\rm{ }}{H_3}{O^ + }\]

4. The common acids which we can use in the laboratory are—Hydrochloric acid (HCl), Nitric acid (\(HN{O_3}\)) and Sulphuric acid (\({H_2}S{O_4}\)).

Uses of Acids

Acid	Uses
Sulphuric Acid, H2SO4	Used as solvent
Formic Acids, HCOOH	Used for tanning and dyeing
Hydrochloric Acid, HCl	Used as Cleaner
Benzoic Acid, C6H5COOH	Used as food preservatives and in dyeing
Nitric Acid, HNO3	Used in Fertilizer, dyes, and plastics

Bases

1. Bases are substances that release hydroxyl ions when combined with water to form an aqueous solution. 

2. They exhibit a pH level above 7 and turn red litmus to blue. 

3. A base has a basic group that separates in an aqueous media or a dissociable hydroxyl group (Arrhenius base). 

4. Metal hydroxides are mostly basic and rapidly produce hydroxyl ions in an aqueous solution. The majority of basic hydroxides are formed by alkali metals and a few alkaline earth metals.

\[BOH\left( {aq} \right){\rm{ }} \to {\rm{ }}{B^ + }\left( {aq} \right){\rm{ }} + {\rm{ }}O{H^ – }\left( {aq} \right)\;\]

5. Sodium hydroxide, potassium hydroxide, and ammonium hydroxide are some examples of bases. 

Uses of Bases

Bases	Uses
Potassium Hydroxide, KOH	Soaps and Batteries
Ammonia NH3	Fertilizer
Calcium Hydroxide, Ca(OH)2	Mortar and Plaster
Magnesium Hydroxide, Mg(OH)2	Detergent
Sodium Carbonate Na2CO3	Detergent

Properties of Acids and Bases

Properties	Acid	Base
Taste	Sour	Bitter
pH value	less than 7	greater than 7
Electric conductivity	Good conductor	Good conductor
Test with litmus paper	Turn red litmus to blue.	Turns blue litmus to red.
Touch	–	Slippery

The similarity between an acid and a base

1. They both react with litmus.

2. They both are compounds

3. Likewise, they both release ions in their solution

4. Forms salt and water when combined. For example, when Ammonium hydroxide reacts with Hydrochloric acid, it gives Ammonium Chloride. 

\[N{H_4}OH{\rm{ }}\left( {aq} \right)\;{\rm{ }} + {\rm{ }}HCl\left( {aq} \right)\;\, \to {\rm{ }}N{H_4}Cl{\rm{ }}\left( s \right){\rm{ }} + {H_2}O{\rm{ }}\left( l \right)\]

Summary

Acidic substances are usually identified by their sour taste. An acid is a molecule which can donate an \({H^ + }\) ion and can remain energetically favourable after a loss of \({H^ + }\). Acids are known to turn blue litmus red.

Bases, on the other hand, are characterized by a bitter taste and a slippery texture. A base that can be dissolved in water is referred to as an alkali. When these substances chemically react with acids, they yield salts. Bases are known to turn red litmus blue.

Frequently Asked Questions

1. Which acid or base, when dissolved in water, releases hydroxyl ions?

Ans. Bases are chemicals that dissolve in water to produce hydroxyl ions, or \(O{H^ – }\), and are also referred to as alkalis.

2. What kind of salt is produced when a strong acid reacts with a weak base?

Ans. The salts are known as acidic salts because they are formed when strong acids and weak bases react. Every salt has a pH that is under 7. Similar to this, many salts’ aqueous solutions have a pH of 7 and are naturally neutral.

3. Which has a sour taste between acid and base?

Ans. Bases have a bitter taste, while acids have a sour taste. Acid always has a pH value lower than 7, which causes it to turn blue litmus paper red.

Introduction

We can see the effects of oxidation and reduction reactions in daily life. This has a variety of consequences. Some of its instances, such as burning fuels, digestion of food in our bodies, and so on, are boons to humanity and highly beneficial to the continuation of life.

Do you know, in human bodies, respiration is the oxidation reaction? During this process, the food is oxidized and produces energy. On the other hand, some of its effects are highly harmful, such as air pollution from burning fuels, food rancidification, metal corrosion, etc.

Oxidation Reaction Examples

In many ways, oxidation reactions have an impact on our daily lives. While some of them are advantageous, others have unfavourable effects. The following are some typical oxidation reaction examples:

• In human bodies, respiration triggers an oxidation reaction. During respiration, food is oxidized to produce energy.
• Metal corrosion is a type of oxidation reaction.
• Fried foods acquire a bad flavour and a bad odour after being exposed to air for a long time (rancidity).
• Any substance that burns or is consumed undergoes an oxidation reaction, which always results in the production of energy. 
• Energy is produced by the combustion of various fuels in a variety of domestic and industrial processes.

Oxidation Reaction’s Effects on Daily Life

Now let us discuss oxidation reactions in everyday life. Have you ever noticed how oxidation processes affect your daily life? Maybe you have, but you’re not aware that they involve an oxidation process.  Rusting is an example of an oxidation reaction that you may be familiar with:

Rusting

A type of metal corrosion is rusting. When air and moisture in the surrounding environment interact with a metal, corrosion results. It is a result of the metal oxidizing. Because iron oxidizes in the presence of air and water to produce hydrated iron oxide, it rusts (\(F{e_2}{O_3}.x{H_2}O\)). The metal surface develops a reddish-brown layer of iron oxide.

\[4Fe{\rm{ }} + {\rm{ }}3{O_2}\, + {\rm{ }}2x{H_2}O \to F{e_2}{O_3}.x{H_2}O{\rm{ }}\left( {Rust} \right)\]

Long-term corrosion or rusting harms metal-bodied constructions. Rust develops on car bodies, bridges, railings made of iron, and ships. The metal can be kept from corroding by having paint or enamel applied to its surface.

Rancidity

The rotting of food is another typical consequence of oxidation in daily life. When foods with fats or oils are left out in the air for a long time, they begin to rancid. This is caused by the food’s fatty acids slowly oxidizing in the air, which leaves the food tasting and smelling unpleasant. The phenomenon known as “rancidity” occurs when food items are exposed to the air and undergo colour, texture, taste, and odour changes due to atmospheric oxidation.

Combustion

One of the most significant oxidation reactions is combustion. Since energy is a by-product of all combustion reactions, these processes are known as exothermic reactions because they emit heat energy.

• Energy is a necessity for our society. Any fuel that burns in the presence of air, including kerosene, petroleum, coal, wood, and charcoal, produces heat. Methane in natural gas is burned during combustion, releasing carbon dioxide and water when there is too much oxygen.
• Thermal power plants burn coal to create electricity, while natural gas is used in kitchens. We can observe how important redox reactions are to maintaining our quality of life in this way. Fuel combustion generates thermal energy, which not only powers our economy but also keeps us warm and alive. 

\[C{H_4}\, + \,2{O_2} \to C{O_2} + {\rm{ }}2{H_2}O\]

• Animals need the heat energy that they produced during food digestion. The human body also acts as a machine that burns and oxidizes all the food that is given to it to produce energy. The body gets its energy from sugar or carbohydrates like glucose (C6H12O6), fructose, and starch. When sugar and oxygen are burned, carbon dioxide, water, and heat are produced.

\[{C_6}{H_{12}}{O_6} + {\rm{ }}6{O_2} \to {\rm{ }}6C{O_2} + {\rm{ }}6{H_2}O{\rm{ }} + {\rm{ }}energy\]

 The harmful effect of combustion

Despite the many benefits of combustion, its negative impact on our life needs to be properly addressed. Fossil fuel combustion results in hazardous vapours that contain dangerous gases such as carbon monoxide, nitrogen oxides, sulphur dioxide, and sulphur trioxide. When released into the atmosphere, fumes and smoke from furnaces and car exhaust severely pollute the air. It degrades our health and does direct harm to our bodies.

Summary

In addition to harming food, oxidation also harms metals. Corrosion is the term used to describe the harmful effect of oxidation on metals, and rancidity is used to describe it on food. Thus, the corrosion of metals and the rancidity of food are two common outcomes of oxidation reactions that are seen in daily life. Aerial oxidation is another name for the oxidation that oxygen in the air causes. The prevention of rancidity, corrosion, and their effects on daily life were all covered in this article.

Frequently Asked Questions

1.What happens when something oxidizes?

Ans. The deterioration in the quality of food products, including off flavours and odours, is caused by oxidation, a chain reaction that takes place in the presence of oxygen. It depends on how the product is made, how it is packaged, how it is stored, and what ingredients are used.

2. What distinguishes burning from combustion?

Ans. Combustion is just an oxidation reaction that releases energy; burning is a type of combustion that is followed by the evolution of gas and is distinguished by flame. Burning is combustion that results in a fire, but not all combustions result in a flame.

3. How is oxygen transported to the cell, so it can keep breathing?

Ans. Humans breathe in oxygen, which travels via many alveoli in the lung (tiny air sacs). These air sacs transfer oxygen into the blood, which carries it to the cells. The oxygen from the lungs is transferred to the blood, where it connects with the red blood cell’s haemoglobin and travels to all the cells where it is discharged. The lungs receive the waste carbon dioxide from the cells and transfer it there for expiration.

Introduction

Something that has mass, takes up space, and can be sensed by our five senses is said to be matter. We can put it simply by saying that the things we see and feel around us matter. There are different states of matter. Because of the characteristics of the constituent particles and how they interact, each of these forms of matter has a unique feature. Atoms and molecules make up these particles. The basic elements of matter, atoms, are capable of independent existence. The neutron, proton, and electron subatomic particles that make up each atom determine the characteristics of the atoms.

Matter

The matter is a combination of two or more pure elements. The classification of the material into solids, liquids, and gases is based on its physical characteristics. Its classification into elements, compounds, and mixtures is based on its chemical characteristics. Our surroundings can be either geographical or man-made. Geographical surroundings are formed by nature and affect the social and economic climate, while man-made environments are those that are man-made.

All living and non-living things are called matter because they contain mass and take up space, all forms of life, including gases like oxygen and hydrogen, are referred to as matter. The DNA in our cells, the ground we are standing on, electrons revolving around a nucleus, or any other object is matter.

Types of Matter

The matter is divided into the three categories below based on its physical nature:

• Solids: Particles in solids are so closely packed and held in place by extremely strong intermolecular interactions that only vibratory motion is possible. They have a distinct volume and shape. Wood, iron, etc. are some examples.
• Liquids: Compared to solids, liquids have more freedom of movement due to the weak intermolecular interactions that allow for particle movement. Despite taking on the shape of the container they are poured into, they have specific volumes. Examples include milk, water, etc.
• Gases: These molecules move very freely and have a weak intermolecular interaction. The distance between them is also very large. They fill the container in which they are placed because they lack a set shape and a volume. Examples include hydrogen and methane.

Applying pressure and changing the temperature can modify the nature of the three matter states mentioned above. There are particles in a matter that have kinetic energy; this energy rises with temperature. In solids, the distance between particles and kinetic energy is the smallest, whereas it is greatest in gases. The three types of matter that make up our environment are interchangeable through temperature changes. For instance, changing the temperature will cause ice to turn into water and back again.

Subatomic Particles

Protons, neutrons, and electrons make up the primary units of matter, known as atoms. Protons have a positive charge, whereas electrons have a negative charge, making neutrons neutral particles with no charge. The nucleus of an atom is made up of neutrons and protons, and electrons revolve around this nucleus in their respective orbitals. The quantity and configurations of these subatomic particles greatly influence the stability and characteristics of the atom.

Summary

The Panch Tatva, or air, earth, fire, sky, and water, was the system used by our ancient Indian thinkers to categorize matter. There are billions of atoms in every gram of matter. The matter is everything that has mass and takes up space. Matter is composed of particles that are always moving and have different properties in each of the three states of matter. The particles of matter are very tiny and have space between them.  The three types of matter that make up our environment are interchangeable through temperature changes.

Frequently Asked Questions

1. What features do matter particles have?

Ans: The characteristics of matter particles are given below:

a) The intermolecular space that particles have is one of their distinguishing characteristics.

b) Intermolecular force exists among particles.

c) Matter is made up of moving particles.

2. In comparison to solids, liquids typically have a lower density. You must have seen that ice floats on water, though. Why?

Ans: Although ice is a solid, due to its structure, it has a lesser density than water. Ice floats on water because its molecules form a cage-like structure with lots of empty spaces.

3. How can water stored in a matka (earthen pot) cool throughout the summer?

Ans: Since the clay pot has many pores and is porous, the water seeps out of them and evaporates on the pot’s surface, which has a cooling effect. This chills the pot, which in turn causes the water inside to cool.

Introduction

The Mughals built their empire in the Indian subcontinent from the sixteenth to the eighteenth centuries. They mostly achieved this through military conquests, but they continued to solidify their position by keeping diplomatic ties with other kingdoms. When the Mughal kingdom reached its pinnacle, other kingdoms began to recognise its authority, formed allies with the Mughal emperor, and merged with the Mughal empire. The rulers who readily merged with the Mughal empire was respected and honoured. In this way, the Mughal empire grew and ruled most parts of India for a very long time.

Mughal Relations with other rulers

• The Mughal state began to prosper and eventually attained its zenith. They adopted a policy of conquering kingdoms that refused to recognize their rule  through military operations.
• However, many nations accepted the Mughal empire’s subjection after learning of their strength and splendour. 
• The Mughals honoured the devotion of such kings who accepted their authority during the construction of the Empire.
• The Mughals let them keep their privileges in place of paying annual tributes, and on the other hand, gave members of that clan important positions in the court.
• In this way, the Mughals maintained a balance of power by not humiliating kingdoms that were annexed and submerged into the Mughal empire.
• Mughals had an extraordinary relationship with the Rajputs, this was so because King Akbar considered Rajputs as the primary concern which can hinder the growth of the Mughal Empire.

Mughal relations with Rajputs

Regarding Mughal connections with the Rajputs, it was Akbar who realized that the Rajputs’ assistance was essential for expanding and consolidating his kingdom.

Prior to him, Babur and Humayun had no clear policy to embrace the Rajputs; instead, Babur grew their empire by overthrowing Rana Sanga (of Mewar) and Medini Rai (Chanderi). Similarly, Humayun was also unable to maintain cordial ties with Rajputs despite his marriage to a Rajput princess and  Rani Karmavati (of Mewar’s) offer to accept him as a brother.

He made an effort to gain the Rajput’s trust in the following ways:

• The specific Rajput policy was developed by Akbar as a part of his empire-building efforts.
• He cultivated his relationships with Rajput’s through marriages. He married several Rajput princesses.
• He also married off his son, prince Salim, to the daughter of  Bhagwan Das of Amber.
• Rajput lords like Raja Todar Mal, Raja Birbal, and Raja Man Singh received significant posts in his army and government.
• He allowed the Rajput rulers that they could retain their kingdom and continued to rule by accepting Akbar’s overlordship and paying him regular tributes.
• Akbar adopted a wise strategy of refraining from interfering in the internal issues of the Rajputs.
• Rajputs were permitted to practise their religion, construct temples, and participate in festivals during King Akbar’s rule.
• King Akbar also abolished jizyah and won the trust of various Rajputs.
• Not all Rajputs embraced Mughal rule or made friends with them; some Rajput kingdoms posed a serious threat to the Mughals and had to be forcibly incorporated into the Mughal Empire. 
• Even though these kingdoms were defeated, these Rajputs were not humiliated; rather, they were honoured, and their territory was given to them as watan jagir during Akbar’s reign. 

King Akbar is referred to as “the real founder of the Mughal Empire” since his this Rajput policy during the 16th and 17th centuries was one of the key causes of the Mughal empire’s stability and continued expansion.

Summary

The way the Mughals interacted with other kings was crucial to the growth and stabilization of the Mughal Empire. Babur and Humayun held a neutral view of other kings, particularly Rajput’s, as they did not see them as the main obstacle to the empire’s growth. But after Akbar came to power, the Mughals’ perspective on Rajput’s started to alter. As a result, he maintained cordial ties with Rajput’s by granting them special privileges because he saw them as the greatest threat to the Mughal empire. King Akbar respected and honoured all the various clans which had surrendered to the Mughal empire, he not only gave those emperors respectable positions in the Mughal court but despite of conquering their land he allowed the respective rulers to run their own kingdom. Jahangir and Shajahan kept this liberal attitude toward Rajput’s, but as Aurangzeb came into power he destroyed all relations with the Rajput’s and brought the downfall of the Mughal empire.

Frequently Asked Questions

1. Explain the term Watan Jagir.
Ans: Watan jagir is the name for the substantial autonomy that the Rajput chieftains received in their native regions even after the Mughals took control of the region, provided that they were willing to recognise Mughal rule.

2. What was Aurangzeb’s religious policy?
Ans: The fundamental goal of Aurangzeb’s strict religious policy was to convert India into an Islamic nation. For that he did the following-

• He took anti-Hindu measures like destroying temples, imposing jizyah, and expelling Hindus from important posts.
• He urged individuals to become Muslims to be exempt from numerous taxes.
• His religious policies caused a great deal of division and sparked a number of revolts by Rajputs, Sikhs, Jats, and Satnamis.

3. What does sovereignty mean to you?
Ans: The term “sovereignty” describes the absolute power of one person to run a state.

Introduction

The first humans were hunters and gatherers who mainly relied on hunting for food. These hunter-gatherers made up a small group of no more than 100–150 individuals. They used to wander about looking for food. There were many early humans living there at the time- Neanderthals, homo sapiens, homo Rhodesians, etc. Only Homo sapiens survived the onset of the Stone Age, around 50000 BCE, and began to rule the planet. Early modern humans are known as Homo sapiens. The people that now inhabit the earth are descended from these homo sapiens. These are The lone surviving member of the human species, which till today rule the life of modern human beings started to develop in the early stone age and further developed in middle the stone age.

Stone age

The Stone Age, which spans roughly from 5,000 BCE to 4000 BCE, was a time when humans were primarily involved in hunting and gathering. Three distinct phases make up the stone age:

• Paleolithic or old stone age.
• Mesolithic or middle stone age.
• Neolithic or the New Stone Age.

Old Stone Age- This age began as a result of human evolution and population growth. It is also known as the Palaeolithic age. The early stone age, which lasted from about 500,000 BCE to 10,000 BCE, was divided into three stages:

• Primitive stone age
• Mid-Paleolithic period
• Older Stone Age, upper

Middle stone age-This is often known as the Mesolithic age, lasted from 8000 BCE to 10000 BCE. During this time, hunter-gatherers began to create new varieties of stone and bones for use in hunting.

New Stone Age– It is also known as Neolithic age .This period, which saw the development of agriculture and other metals like copper, bronze, and iron, lasted from around 8000 BCE to about 4000 BCE. Hunter-gatherers began to employ stone blades, and various other tools during this time.

Fire and cooking

• Richard Wrangham is an anthropologist from the United States who has investigated the history of fire and the evolution of mankind.
• He has claimed that the homo sapiens and Neanderthals learned the ability of controlling fire from the Homo Erectus, who discovered fire around 1.8 million years ago.
• The ability to control fire is the main reason which distinguishes humans from all other living organisms. Fire was the revolutionary innovation of the human.
• Humans alone have the intelligence to burn and control fire, and they made use of this technology to cook fruits, vegetables, meat etc.
• He claimed that prior to the discovery of fire, human teeth were too large and the digestive system, along with a small brain, was overly complex.
• However, as people began to cook, tooth size began to decrease, and the digestive tract became less complex as cooked food can be easily digested. Hence more energy is now available for use by the brain. This has resulted in increasing the size of the human brain and also its intelligence.

Humans and Tools

• Early stone tools have recently been discovered at the shore of Lake Turkana (Kenya), around 2015.
• Stone tools’ carbon dating indicated that they were around 3.3 million years old.
• The discovery shows that Australopithecus afarensis or Kenyanthropus platyops are the earliest human species to have employed these tools.
• Recently, it has been proposed that Homo Erectus, was the first human to use tools. Previously, it was thought that Homo Habilis was the first human to invent tools.
• The tools made by the early man was primarily used for digging, cooking, and hunting.
• Hunting provided people with their main source of energy, therefore most of the time their tools were used for this purpose.
• The earliest humans made tools in such a away that one side of the tool had a narrow shape and was usually sharp egded and the other side was utilized as an handle. 
• The hunter-gatherers initially started out using raw stone to hunt the animal, but through time they began to learn how to cut the stone in ways that made it a better tool.
• Following techniques are used for making tools-
  • Direct percussion flaking technique: This method involves directly striking one stone with another stone to shatter it into the desired shape.
  • Indirect percussion flaking techniques: With the help of this technique more complex tools are created. This method uses indirect hitting the stone cutting purposes.
  •  Grinding and Polishing: Blades, bows, arrows, and other objects are made using the grinding. Polishing is occasionally employed to make something sharp and add aesthetic value.

• Bones, Wood and Stone were the common materials which were used for making tools. Stone tools were the best out of the three.
• Various tools were made which were used for cutting meat and bones. Some tools were used to scarpe the bark of trees and animal skins. Some tools were also used for chopping purposes.
• Spears and arrows were used for hunting animals. They had a stone edge which was sharp and killed the animals. This stone edge was attached to a long wooden or bone piece which acted as an handle and helped in launching the tool easily.
• There were specialized tools for chopping firewood.

Summary

The first humans were hunter-gatherers who relied on hunting for their food requirements. The development of human tools is categorized by researchers in the various epochs of human growth, for instance, the old stone age of human history has tools that are not sophisticated but as the years passed tools became advanced and very specific for particular purposes. Humans first began to create sophisticated tools to hunt animals. The copper, bronze, and iron ages followed the stone age. Humans have used different tools in each of the three ages. Common tools that were used for hunting were arrows and spears. These tools were either made from stone, bone or wood.

Frequently Asked Questions

1. How did prehistoric people make tools?
Ans: The sole tools used by the giant apes and the earliest human ancestors were likely sticks and stones. The first tools made by early humans were from stones that had been broken and smashed to create a sharp edge on one end and which can be use for hunting purposes.

2. What do you mean by the bronze age?
Ans: The bronze era is the period that followed the end of the stone age. The bronze age, which lasted roughly from 3300 BCE to 1200 BCE, is when people first learned how to employ bronze, a form of metal, in everyday life

3. What was one of the most crucial tools used by prehistoric humans?
Ans: In the Ancient tradition, sharp-edged stone flakes created during the process of making core tools were likely the most essential tools. Without any further alterations, these basic flake tools were utilized as knives.

Introduction 

The transition from primitive humans to modern humans involved various modifications. Throughout this process, several human lifestyles were observed. They transitioned from being food gatherers to producers. They made numerous discoveries that are still in use in modified form. They then started to create shelters for a prolonged stay in a particular location as farming advanced. They are thought to have originated in Africa and then gradually spread to other regions of the world. These people initially lived in tiny groupings but over time shifted to bigger groups. With that, the concept of villages was developed and cultural adaption became simpler.

Lifestyle and Culture of early modern humans

• In the beginning, humans were hunter-gatherers. They moved around extensively and used stone weapons to hunt wild animals and obtain harvest from trees.
• To protect themselves from the harsh weather, they used to cover themselves in either animal skins or leaves or bark of trees.
• As they progressed, they discovered fire and learned to use it for many things.
• Early modern humans shifted toward farming as the climate on earth warmed up.
• Some of these humans were engaged in heavy hunting, while others were in the early stages of domestication.
• Early modern people raised crops like corn, wheat, and barley and became food producers.
• The notions of family and community also emerged when these humans  began residing in small communities. In turn, villages were established for safety and cooperation of the people.

Population Trends Beginning About 100,000 Years Ago

• Researchers and historians have estimated that early modern humans, or Homo sapiens, originated in various parts of Africa between 200,000 and 100,000 years ago.
• For many years, these modern humans continued to produce crude, primitive stone tools, just like their ancestors.
• According to scientific studies, there was a gap period between, when people start to look modern and when they start behaving modern.
• Stephen Shennan, an archaeologist at London University, believes that cultural change is what allowed humans to socialize and begin residing in large groupings. This paved the road for their modernization.
• Population growth in Africa made it simpler for people to establish connections with nearby communities. Most likely, they switched partners for mating. This ultimately resulted in the exchange of ideas and genetic material which paved way for newer creations and inventions.
• Homo sapiens first migrated from Africa to Europe some 45,000 years ago.
• Neanderthals were already present in Europe when modern people first arrived. They outnumbered their rival Neanderthals and eliminated them from Europe.
• The population started to drop around 25,000 years ago, during the Ice Age, when the ice almost completely cover the northern Europe. However, when this era came to a conclusion, the population once more increased.
• With the introduction of farming and established life 11,000 years ago, female fertility also increased. As a result, the population reached up to 6 to 7 million on the beginning of the Neolithic period.

Early Modern Man Society

• Modern humans initially preferred to remain in small groups, but they gradually began to form big groups as a result of mutual ties.
• In these groups, everyone had access to resources like food and tools.
• During that time, there was still no sense of personal or individual control and hence they used to be a danger to other groups.
• When the large groups of humans divided themselves into villages, all of these things started to change. They  became more sophisticated, and gradually the idea of the family also emerged.

Summary

Numerous studies have been conducted to examine- the way of life, culture, and population growth of early modern humans. Early modern people began to adapt to various habitats and surroundings as they began to spread across the globe. A variety of lifestyles could be observed as a result of the shifting climate and farming activities.

They developed farming habits and cultivated various crops for food and nutrition. People stayed in the area longer as a result of these farming activites. This caused a transition from a nomadic to a settled lifestyle. Also the concept of family and community developed during this era.

Frequently Asked Questions

Which is the World’s Oldest “Village”?
Ans: The Mladec caverns are located in the Prague region of the Czech Republic is regarded as the world’s  oldest “village” . Many early modern human skeletons or remains can be found in these caves. The bones discovered here were 31,000 years old.

Researchers attempted to study the DNA of these fossils but were unable in doing so. They did, however, manage to analyse the DNA of two specimens and discovered that those did not belong to the “homo” series.

2. When and what is the reason of human population explosion which occured 60,000-80,000 years ago?
Ans: According to several archaeological studies, the Neolithic era is responsible for the expansion of the human population. In this period the change to domestication led to the development of more sophisticated procedures of agriculture and settlements, opening the path for population rise from 4-5 million to 60-70 million. But. according to a study from the University of Paris, population growth occurred considerably earlier than the farming or Neolithic periods, more likely  population expansion occurred in the Paleolithic hunter-gatherer period.

3. What did the early ancestors eat?
Ans: The earliest hominins likely had an omnivorous diet similar to that of modern chimpanzees, which includes substantial amounts of fruit, leaves, flowers, bark, insects, and meat.

Introduction 

The origin and advancement in the physical features of human ancestors have been termed human evolution.  According to this theory, early humans went through a number of stages which converted them from prehistoric man to modern humans. Gradually the development in their brain size permitted them to use their physical attributes more skillfully. Early humans underwent many changes during the Neolithic period. They changed from hunters and gatherers to food producers, from living in trees or caves to becoming settlers, and from nomads to properly established people. Through this evolutionary process, humans developed the skill of managing resources efficiently and learnt the ability to remain in social work with other unknown individuals.

Evolution

Evolution is the gradual change in the inherited traits of  populations over many generations. These traits are the expressions of genes, which are passed down through from parent to offspring during sexual reproduction. This is the process by which a living organism changes and develops from their ancestors. Natural selection, mutation, gene flow, and genetic drift are a few of the methods which bring about evolution in a species. As a result of these processes, species emerge, grow, and adapt to their physical and social environments.

Evolution of Humans

Evolution of humans occurred from apes. Most scientists believe that humans and apes must have developed from the same creature because they share so many characteristics, such as long arms and a large brain. These  ape like creatures were called hominids.

Australopithecus Afarensis and Lucy

• The name Australopithecus refers to the earliest hominid. Australopithecus africanus, Australopithecus robustus Boisie, and afarensis are some of the different types of Australopithecus that have been identified through fossils.
• Australopithecus afarensis fossils have been discovered from Etopia.
• Experts have seen the last phase of bipedal movement in this species.
• Despite being able to stand upright, these humans still had certain ape-like characteristics.
• The most well-known Australopith is “Lucy“. It is a skeleton of Australopithecus afarensis which 3 million years ago was discovered in 1974 
• It was found by Donald C. Jhonson and his student Tom Gray at the site of Hardar in Ethiopia.
• While looking for animal bones, Johnson and Gray unintentionally discovered a little arm bone fragment and recognized that it belonged to hominids.

Homo Habilis

• The earliest known fossils of Homo are known as “homo Habilis,” and they were found in Kenya.
• The genus homo is different from Australopithecus, as its brain was bigger in size.
• Two million years ago, Homo Habilis possessed a larger brain that was nearly 800 cc in size.
• It was believed that Homo Habilis made various tools.
• They were first classified as members of the australopithecine family, but an in-depth research, later demonstrated that they should actually be considered early human specimens.

Homo Erectus

• A new species known as Homo Erectus emerged after the origin of Homo Habilis.
• It had a larger brain, that was 1000cc in size.
• They were considerably bigger and taller than Homo Habilis and now they could stand straight.
• Their grip improved as their fingers developed and this enabled them to firmly grasp objects.
• They began to travel enormous distances and build tools with great proficiency.

Homo sapiens Neanderthalensis

• Gradually Homo erectus perished nearly around 400,000 years ago.
• Around 125,000 years ago, a new species of Homo appeared on the human evolutionary process the Homo Neanderthals or Homo sapiens Neanderthals.
• In the 20th century, their fossils were discovered in Germany.
• Neanderthal brain continued to grow in size, and  evidence of ‘culture’ began to emerge
• However, Neanderthal skulls were very distinct from those of modern humans.

 Homo Sapiens Sapiens

• Then emerged the Homo sapiens sapiens, also known as the “thinking man” or “wise man,” from which modern humans evolved.
• They had a 1350cc brain, which allowed them to create more sophisticated tools.
• The homo sapiens sapiens began to interact with their social surroundings and live in groups.
• To dwell longer in a place, they started constructing proper and strong  shelters.
• They were likely the first living things to speak what we now refer to as language, and it proved to be helpful for them.

The Neolithic Revolution

• The beginning of the Neolithic period can not be traced to a particular date as it was emerging at different times in different places.
• It is one of the third stages of development and it saw a evolution in the early humans’ way of existence.
• The invention of agriculture was the most significant aspect of this period. Now, they no longer need to go around in quest of food because they have learned to cultivate their own food.
• Permanent settlements were eventually established as a result.
• Along with this, they now started to domesticate animals for their own purposes; this was also the time when the wheel was invented.

Summary

Human evolution is a long process and it took millions of years to transform primitive humans into present-day humans. As per numerous scientific investigations, it is thought that humans have developed from ape-like species. They could not even walk straight and they used to live like animals. As the brain grew in size over time, the evolution of the homo sapiens began. Their social conduct also evolved gradually. Additionally, they developed excellent toolmaking skills. Humans could also store knowledge due to their more advanced brains. This enhanced the speed of cultural adjustment and now modern humans were no more dependent on biological advancements.

Frequently Asked Question

1. What color was the original human being on earth?
Ans: Early humans had a pale skin, similar to the chimpanzee(closest relative of humans), . Dark skin was first a feature of early Homo sapiens which developed between 1.2-1.8 million years ago.

2. How come people have two legs?
Ans: One of the factors, that allowed humans to evolve from their prehistoric ape-like forebears was the ability to walk on two legs. Being able to move around on two legs saved energy and freed up the arms for tasks like hunting, making simple tools, and interacting with objects.

3. Are there still Neanderthals existing?
Ans: Around 430,000 years ago, fossils resembling Neanderthals were first discovered. The earliest Neanderthals are thought to have existed between 130,000 and 40,000 years ago, beyond which no physical proof of them can be found.