In a Face Centred Cubic (FCC) unit cell, atoms are present at all eight corners and at the centres of all six faces.


The contribution of an atom at the corner to one unit cell is \(1/8\).


Total contribution from 8 corners = \(8 \times \frac{1}{8} = 1\) atom.


The contribution of an atom at the face centre to one unit cell is \(1/2\).


Total contribution from 6 face centres = \(6 \times \frac{1}{2} = 3\) atoms.


Total number of atoms per unit cell = \(1 + 3 = 4\) atoms.
Quick Tip: Remember the 'Z' values: Simple Cubic = 1, BCC = 2, FCC = 4, HCP = 6.

Packing fraction is the fraction of total volume of the unit cell occupied by the constituent particles (spheres).


For a Body-Centred Cubic (BCC) unit cell, the packing efficiency is calculated using the relation \(4r = \sqrt{3}a\), where \(r\) is the radius and \(a\) is the edge length.


Packing Efficiency = \(\frac{Volume of 2 atoms}{Volume of unit cell} \times 100 = \frac{2 \times \frac{4}{3}\pi r^3}{a^3} \times 100\).


Substituting \(a = \frac{4r}{\sqrt{3}}\), the efficiency comes out to be approximately \(68%\).


In decimal form, the packing fraction is \(0.68\).
Quick Tip: Empty space in BCC is \(100 - 68 = 32%\).

Ferromagnetic substances are those that are strongly attracted by a magnetic field and can be permanently magnetized.


This property arises due to the spontaneous alignment of magnetic domains in the same direction.


Iron (Fe), Cobalt (Co), Nickel (Ni), Gadolinium (Gd), and \(CrO_2\) are standard examples of ferromagnetic materials.


Copper (Cu) is diamagnetic, NaCl is diamagnetic, and MnO is antiferromagnetic.
Quick Tip: Ferromagnetism is the strongest form of magnetism and persists even after the external field is removed.

Frenkel defect (dislocation defect) occurs when an ion (usually the smaller cation) is displaced from its lattice site to an interstitial site.


This defect is common in ionic solids where there is a large difference in size between the cation and anion.


Silver halides like \(AgCl\), \(AgI\), and \(AgBr\) exhibit Frenkel defects because \(Ag^+\) ions are small enough to fit into interstitial spaces.

\(NaCl\) primarily shows Schottky defect because the sizes of \(Na^+\) and \(Cl^-\) are comparable.
Quick Tip: Frenkel defect does not change the density of the crystal, unlike Schottky defect.

Abnormal colligative properties (like osmotic pressure) are observed when the solute undergoes association or dissociation in the solvent.


Urea, Glucose, and Sucrose are non-electrolytes; they do not dissociate or associate in water, so their van't Hoff factor (\(i\)) is 1.


Common salt (\(NaCl\)) is an electrolyte that dissociates into \(Na^+\) and \(Cl^-\) ions in water.


Since the number of particles increases upon dissociation, the observed osmotic pressure is higher than the calculated value, hence it is "abnormal".
Quick Tip: \(i > 1\) for dissociation (electrolytes) and \(i < 1\) for association (e.g., benzoic acid in benzene).

According to the law of elevation in boiling point, \(\Delta T_b = K_b \cdot m\), where \(m\) is the molality of the solution.


If the molality (\(m\)) is 1 (one molal solution), then \(\Delta T_b = K_b\).


The constant \(K_b\) is known as the Molal Elevation Constant or the Ebullioscopic Constant.


Cryoscopic constant (\(K_f\)) refers to the depression in freezing point for a one molal solution.
Quick Tip: Ebullioscopic constant depends only on the nature of the solvent, not the solute.

The lowering of vapour pressure is a colligative property, which depends on the number of solute particles in the solution.


Higher the number of particles, greater will be the lowering of vapour pressure, and thus lower will be the final vapour pressure of the solution.


Let's check the van't Hoff factor (\(i\)) for each:

(A) \(BaCl_2 \rightarrow Ba^{2+} + 2Cl^-\) (\(i = 3\)).

(B) Urea \(\rightarrow\) Non-electrolyte (\(i = 1\)).

(C) \(Na_2SO_4 \rightarrow 2Na^+ + SO_4^{2-}\) (\(i = 3\)).

(D) \(Na_3PO_4 \rightarrow 3Na^+ + PO_4^{3-}\) (\(i = 4\)).


Since \(0.1 M Na_3PO_4\) produces the maximum number of particles (\(0.4 M\) ions), it will have the lowest vapour pressure.
Quick Tip: Vapour pressure is inversely proportional to the number of particles (\(i \times M\)).

Mass of solution = 234.2 g.


Mass of solute (sugar, \(C_{12}H_{22}O_{11}\)) = 34.2 g.


Mass of solvent (water) = Mass of solution - Mass of solute = \(234.2 - 34.2 = 200\) g = 0.2 kg.


Molar mass of sugar (\(C_{12}H_{22}O_{11}\)) = \((12 \times 12) + (22 \times 1) + (11 \times 16) = 144 + 22 + 176 = 342\) g/mol.


Number of moles of sugar = \(\frac{Given mass}{Molar mass} = \frac{34.2}{342} = 0.1\) mol.


Molality (\(m\)) = \(\frac{Moles of solute}{Mass of solvent in kg} = \frac{0.1}{0.2} = 0.5\) m.
Quick Tip: Molality is moles per kg of solvent, not solution. Always subtract solute mass from solution mass first.

Faraday's first law of electrolysis states that the mass (\(m\)) of any substance deposited or liberated at any electrode is directly proportional to the quantity of electricity (\(Q\)) passed through the electrolyte.

\(m \propto Q\).


Since \(Q = I \cdot t\) (where \(I\) is current and \(t\) is time), we have \(m \propto I \cdot t\).


Introducing the electrochemical equivalent (\(z\)) as the proportionality constant, we get \(m = z \cdot I \cdot t\).


In the options provided, '\(c\)' is used to represent current (\(I\)). Thus, the equation is \(m = c \cdot z \cdot t\).
Quick Tip: Electrochemical equivalent (\(z\)) is the mass deposited by 1 Coulomb of charge.

Specific conductance (\(\kappa\)) is the conductance of ions present in a unit volume (\(1 cm^3\)) of the electrolytic solution.


Upon dilution, the total volume of the solution increases, but the number of ions per unit volume decreases.


Because there are fewer ions available to carry current in a given volume after adding more solvent, the specific conductance decreases.


Note: This is different from molar conductance (\(\Lambda_m\)), which increases with dilution.
Quick Tip: Dilution effect: \(\kappa\) (Specific conductance) \(\downarrow\), \(\Lambda_m\) (Molar conductance) \(\uparrow\).

Reducing power is the ability of a substance to reduce others by itself getting oxidized.


A substance that has a high tendency to get oxidized acts as a strong reducing agent.


In terms of Electrochemical Series, the lower (more negative) the standard reduction potential (SRP) of a metal, the higher is its tendency to lose electrons (get oxidized).


Among the given values:

A: -3.05 V

B: -1.66 V

C: -0.40 V

D: +0.80 V


Metal A has the lowest (most negative) reduction potential, so it has the highest tendency to lose electrons and thus possesses the highest reducing power.
Quick Tip: Strongest reducing agent = Most negative SRP value. Strongest oxidising agent = Most positive SRP value.

Cells are classified as Primary or Secondary.


Primary cells (e.g., Leclanche cell, Dry cell) are those in which the reaction occurs only once and they cannot be recharged after use.


Secondary cells are those which can be recharged by passing current through them in the opposite direction. They can be used again and again.


Lead storage battery, used in automobiles and inverters, is a classic example of a secondary cell.
Quick Tip: Lead storage battery uses \(Pb\) as anode, \(PbO_2\) as cathode, and \(38% H_2SO_4\) as electrolyte.

The dependence of the rate of a chemical reaction on temperature is quantitatively expressed by the Arrhenius equation.


The equation is: \(k = A \cdot e^{-E_a/RT}\), where:
\(k\) is the rate constant.
\(A\) is the Arrhenius factor or frequency factor.
\(E_a\) is the activation energy.
\(R\) is the gas constant.
\(T\) is the temperature in Kelvin.


This equation shows that the rate constant (\(k\)) increases exponentially with an increase in temperature.
Quick Tip: Generally, for every \(10^\circ C\) rise in temperature, the rate of reaction nearly doubles.

(A) Acid hydrolysis of ethyl acetate is a pseudo-first-order reaction because water is present in large excess.


(B) Saponification of an ester (reaction with \(NaOH\)) is a second-order reaction. Its rate depends on the concentration of both the ester and the alkali: \(Rate = k[Ester][NaOH]\).


(C) Decomposition of \(H_2O_2\) is a first-order reaction.


(D) Decomposition of \(N_2O_5\) is a first-order reaction.


Therefore, option (B) is not a first-order reaction.
Quick Tip: Molecularity of saponification is 2 and its order is also 2.

The rate of a chemical reaction can be expressed in terms of the rate of disappearance of reactants.


For the general reaction \(aA + bB \rightarrow products\), the rate is defined as:
\(Rate = -\frac{1}{a} \frac{d[A]}{dt} = -\frac{1}{b} \frac{d[B]}{dt}\).


To find the value of \(-\frac{d[A]}{dt}\), we rearrange the equality:
\(-\frac{d[A]}{dt} = a \left( -\frac{1}{b} \frac{d[B]}{dt} \right)\).
\(-\frac{d[A]}{dt} = \frac{a}{b} \left( -\frac{d[B]}{dt} \right)\).


Thus, \(-\frac{d[A]}{dt} = -\frac{a}{b} \frac{d[B]}{dt}\).
Quick Tip: Always divide the rate of change of concentration by its stoichiometric coefficient to get the unique rate of reaction.

All natural and artificial radioactive decay of unstable nuclei take place by first-order kinetics.


The rate of decay is proportional only to the number of radioactive nuclei present at that time.


The mathematical expression is \(\frac{dN}{dt} = -\lambda N\), which is identical to the first-order rate law.
Quick Tip: Half-life (\(t_{1/2}\)) for radioactive decay is independent of the initial concentration: \(t_{1/2} = 0.693/\lambda\).

The extent of adsorption of a gas on a solid surface (like charcoal) depends on the ease of liquefaction of the gas.


Gases with higher critical temperatures (\(T_c\)) are more easily liquefiable and are adsorbed more strongly due to stronger van der Waals forces.


Among the given gases, the critical temperatures follow the order: \(NH_3 > CO_2 > CH_4 > H_2\).


Therefore, the volume of gas adsorbed follows the same order: \(NH_3 > CO_2 > CH_4 > H_2\).
Quick Tip: Easily liquefiable gases (polar or high molar mass) are adsorbed to a greater extent than permanent gases like \(H_2\).

The Langmuir adsorption isotherm describes the quantitative relationship between the mass of gas adsorbed per gram of adsorbent (\(x/m\)) and the equilibrium pressure (\(P\)) at a constant temperature.


It is based on the assumption that adsorption is limited to a single layer (monolayer).


The derivation leads to the formula: \(\frac{x}{m} = \frac{aP}{1 + bP}\), where \(a\) and \(b\) are Langmuir constants.


At low pressure, \(x/m \approx aP\) (linear). At high pressure, \(x/m \approx a/b\) (constant).
Quick Tip: Langmuir isotherm is mostly applicable to chemisorption.

Colloids are heterogeneous systems in which the size of the dispersed phase particles is intermediate between that of true solutions and suspensions.


The standard range for colloidal particle diameters is generally defined as 1 nm to 1000 nm (\(10 \AA\) to \(10000 \AA\)).


In some textbooks or board exams, subsets or specific ranges within this are provided. Based on the provided marking in the exam paper, option (D) 10 nm - 1000 nm is the intended correct answer.
Quick Tip: True solutions: < 1 nm. Colloids: 1 - 1000 nm. Suspensions: > 1000 nm.

Colloids are classified based on the physical state of the dispersed phase and the dispersion medium.


Smoke consists of solid particles (like carbon or dust) suspended in a gaseous medium (air).


Therefore, smoke is a solid-in-gas colloid, technically called an "Aerosol".
Quick Tip: Fog and clouds are examples of liquid-in-gas aerosols.

Butter is a colloidal system where liquid droplets (water) are dispersed in a solid fat medium.


Scientifically, it is often classified as a "Gel" (liquid in solid). However, many standard chemistry curricula and exams (including the provided markings) classify it as a "Water-in-oil emulsion" due to its lipid base.


Following the marking in the provided PDF, Butter is an example of an Emulsion.
Quick Tip: Milk is an oil-in-water emulsion, whereas butter is a water-in-oil emulsion.

An emulsifier (or emulsifying agent) is a substance added to an emulsion to stabilize it by reducing the interfacial tension between the two immiscible liquids.


Soaps and detergents are common emulsifiers. They have a hydrophilic head and a hydrophobic tail, which allows them to interact with both water and oil, keeping them mixed in a stable form.


Common salt and urea are not emulsifiers. Oil is one of the phases of an emulsion.
Quick Tip: Natural emulsifiers include proteins, gums, and agar-agar.

Biological catalysts are substances that speed up biochemical reactions in living organisms without being consumed.


Enzymes are protein molecules that act as highly specific and efficient biological catalysts.


Examples include amylase (for starch digestion) and pepsin (for protein digestion).


Carbohydrates are energy sources, amino acids are building blocks of proteins, and nitrogenous bases are components of DNA/RNA.
Quick Tip: Enzymes work by lowering the activation energy of biological reactions.

Shape-selective catalysis depends on the pore structure of the catalyst and the size of the reactant and product molecules.


Zeolites are aluminosilicates with a honey-comb like structure. They act as shape-selective catalysts because only molecules of specific sizes can fit into their pores.


ZSM-5 is a specific type of zeolite used in the petroleum industry to convert alcohols directly into gasoline (petrol) by dehydrating them.

\(V_2O_5, Cr_2O_3,\) and \(MnO_2\) are standard transition metal oxide catalysts but are not shape-selective.
Quick Tip: Zeolites are also used as ion-exchangers in water softening.

The thermite process involves the reduction of metal oxides (like \(Fe_2O_3\) or \(Cr_2O_3\)) using aluminium powder.


Aluminium has a high affinity for oxygen and acts as a strong reducing agent.


The reaction is highly exothermic: \(Fe_2O_3 + 2Al \rightarrow Al_2O_3 + 2Fe + heat\).


The molten iron produced is often used for welding railway tracks.
Quick Tip: Reduction using aluminium is also called Aluminothermy or Gold-schmidt process.

Leaching is a chemical method of concentration where the ore is treated with a suitable reagent to dissolve the metal while leaving impurities behind.


Silver and Gold are extracted using the MacArthur-Forrest cyanide process.


The powdered ore is treated with a dilute solution of \(NaCN\) or \(KCN\) in the presence of air. Silver dissolves to form a soluble complex:
\(4Ag + 8CN^- + 2H_2O + O_2 \rightarrow 4[Ag(CN)_2]^- + 4OH^-\).


The silver is later recovered from the complex by displacement with a more reactive metal like Zinc.
Quick Tip: Hydrometallurgy is the branch of metallurgy that uses leaching and displacement.

Human bones and teeth are primarily composed of calcium and phosphorus.


The main inorganic mineral component is hydroxyapatite, which is a crystalline form of calcium phosphate.


Therefore, Calcium phosphate, \(Ca_3(PO_4)_2\), is the main constituent of bones.
Quick Tip: Phosphorus is often industrially obtained from bone ash, which is about \(80% Ca_3(PO_4)_2\).

Highly reactive metals (like Na, Mg, Ca, Al) are extracted by the electrolytic reduction of their fused salts (chlorides or oxides) because they cannot be easily reduced by chemical reducing agents like carbon.


Sodium (Na) is obtained by the electrolysis of molten \(NaCl\) (Down's process).

Aluminium (Al) is obtained by the electrolysis of \(Al_2O_3\) (Hall-Heroult process).


Iron (Fe) is a moderately reactive metal. It is extracted by the chemical reduction of its oxide ores (\(Fe_2O_3\), \(Fe_3O_4\)) using coke (Carbon) and Carbon monoxide in a blast furnace.
Quick Tip: Metals above Zinc in the reactivity series are usually extracted by electrolysis.

Phosphorus pentoxide exists as a dimer, \(P_4O_{10}\).


It has an extremely high affinity for water and reacts vigorously with it to form phosphoric acid.


Because of this property, it is used extensively as a powerful dehydrating agent in the laboratory. For example, it can dehydrate \(HNO_3\) to \(N_2O_5\) or amides to nitriles.
Quick Tip: \(P_4O_{10}\) is often used in desiccators to keep substances dry.

The acidic character of oxides of Group 15 elements decreases down the group.


As we move from Nitrogen to Bismuth, the electronegativity of the element decreases, and its metallic character increases. Non-metallic oxides are acidic, while metallic oxides are basic.


Since Nitrogen is the most electronegative and non-metallic element in the group, its highest oxide (\(N_2O_5\)) is the most acidic.


Order of acidity: \(N_2O_5 > P_2O_5 > As_2O_5 > Sb_2O_5 > Bi_2O_3\).
Quick Tip: For the same element, the oxide in the higher oxidation state is more acidic.

In Group 16, bond energy generally decreases down the group as the atoms get larger and the bond length increases.


However, oxygen is an exception. The O-O single bond is surprisingly weak compared to the S-S bond. This is due to the small size of the oxygen atom, which leads to strong inter-electronic repulsions between the lone pairs on the two oxygen atoms.


Sulphur is larger, so these repulsions are much less, making the S-S single bond stronger than the O-O single bond.


Therefore, S-S has the highest single-bond energy in this group.
Quick Tip: The strong S-S bond explains why sulphur exhibits a high degree of catenation compared to oxygen.

In its most stable form (rhombic or monoclinic sulphur), sulphur exists as molecules containing eight atoms.


These atoms are arranged in a puckered ring structure, often described as a "crown" shape.


The chemical formula is \(S_8\). Thus, the sulphur molecule is octatomic.
Quick Tip: Phosphorus exists as \(P_4\) (tetratomic), while Oxygen exists as \(O_2\) (diatomic).

The strength of a base is inversely related to the strength of its conjugate acid.


Consider the oxoacids of Chlorine: \(HClO_4\) (perchloric acid), \(HClO_3\) (chloric acid), \(HClO_2\) (chlorous acid), and \(HClO\) (hypochlorous acid).


Acidity order: \(HClO_4 > HClO_3 > HClO_2 > HClO\).
\(HClO_4\) is the strongest acid, while \(HClO\) is the weakest acid.


A weak acid has a strong conjugate base. Since \(HClO\) is the weakest acid among these, its conjugate base (\(ClO^-\)) is the strongest base.
Quick Tip: Greater the number of oxygen atoms in an oxoacid of an element, more stable is the conjugate base, and stronger is the acid.

Fluorine is the most electronegative element in the periodic table. It does not have vacant d-orbitals to expand its octet.


Consequently, fluorine always exhibits an oxidation state of -1 in all its compounds (and 0 in its elemental form \(F_2\)).


Other halogens (Cl, Br, I) have vacant d-orbitals and can exhibit multiple positive oxidation states like +1, +3, +5, and +7, in addition to -1.
Quick Tip: Fluorine is the only halogen that does not form oxoacids where it has a positive oxidation state.

A substance acts as a reducing agent if it can itself be oxidized (increase its oxidation state).


Let's check the oxidation states of the central atoms:

(A) \(N\) in \(NO_2\) is +4. Maximum possible for N is +5. So it can be oxidized further.

(B) \(S\) in \(SO_2\) is +4. Maximum possible for S is +6. So it can be oxidized further.

(C) \(Cl\) in \(ClO_2\) is +4. Maximum possible for Cl is +7. So it can be oxidized further.

(D) \(C\) in \(CO_2\) is +4. Since Carbon is in group 14, its maximum oxidation state is +4. It cannot be oxidized any further.


Since \(CO_2\) cannot be oxidized, it cannot act as a reducing agent.
Quick Tip: If an element is in its maximum possible oxidation state, it can only act as an oxidising agent, never a reducing agent.

The ease of liquefaction of noble gases depends on the strength of inter-atomic van der Waals forces.


As we move down Group 18 (He to Rn), the atomic size and the number of electrons increase. This leads to an increase in polarizability and stronger London dispersion forces.


Stronger intermolecular forces mean higher boiling points and easier liquefaction.


Among the given options, Xenon (Xe) has the largest atomic size and thus the strongest van der Waals forces, making it the most easily liquefied noble gas.
Quick Tip: Helium is the hardest to liquefy and has the lowest boiling point of any known substance.

Peroxy acids contain a peroxide linkage (-O-O-).


(A) \(H_2S_2O_7\) is pyrosulphuric acid (Oleum), which contains an S-O-S linkage.

(B) \(H_2S_2O_8\) is peroxydisulphuric acid (Marshall's acid). It contains a peroxide bond (-O-O-) between the two sulphur atoms.

(C) \(H_2SO_4\) is sulphuric acid.

(D) \(H_2SO_3\) is sulphurous acid.


Another common peroxy acid is \(H_2SO_5\) (peroxymonosulphuric acid or Caro's acid).
Quick Tip: The oxidation state of S in \(H_2S_2O_8\) appears to be +7 by calculation but is actually +6 due to the peroxide linkage.

The large-scale industrial manufacture of nitric acid (\(HNO_3\)) from ammonia (\(NH_3\)) is done via the Ostwald process.


It involves three main steps:

1. Catalytic oxidation of ammonia by atmospheric oxygen to form nitric oxide (\(NO\)).

2. Oxidation of \(NO\) to nitrogen dioxide (\(NO_2\)).

3. Dissolving \(NO_2\) in water to form nitric acid.


Birkeland-Eyde process uses nitrogen and oxygen directly from the air using an electric arc.
Quick Tip: The catalyst used in the first step of the Ostwald process is Platinum-Rhodium (Pt-Rh) gauge.

Gases can be collected over water by the downward displacement of water only if they are nearly insoluble or very slightly soluble in it.

\(H_2, O_2,\) and \(CH_4\) are non-polar molecules and have very low solubility in water, so they are easily collected over water.


Sulphur dioxide (\(SO_2\)) is a polar gas and is highly soluble in water because it reacts with it to form sulphurous acid (\(H_2SO_3\)). Therefore, it cannot be collected by this method.
Quick Tip: Highly soluble gases like \(NH_3, HCl,\) and \(SO_2\) are collected by the displacement of air or in non-aqueous solvents.

Mercury reacts with ozone to form mercurous oxide (\(Hg_2O\)).


The reaction is: \(2Hg + O_3 \rightarrow Hg_2O + O_2\).


As a result of this reaction, mercury loses its meniscus and starts sticking to the sides of the glass container. This phenomenon is known as the "tailing of mercury".
Quick Tip: The mobility and meniscus of mercury can be restored by washing it with water.

Chlorine acts as a powerful bleaching agent in the presence of moisture.


It reacts with water to release nascent oxygen (\([O]\)):
\(Cl_2 + H_2O \rightarrow 2HCl + [O]\).


This nascent oxygen oxidizes the coloured organic matter into colourless products.

Coloured substance + \([O] \rightarrow\) Colourless substance.


Since the process involves oxidation, the bleaching action of chlorine is an oxidising property. This bleaching is permanent.
Quick Tip: Bleaching by \(SO_2\) is due to reduction and is temporary, as the colour returns on exposure to air.

Inert gases (noble gases) belong to Group 18 of the periodic table.


They have a completely filled valence shell, which makes them very stable and chemically unreactive.


The general valence shell electronic configuration is \(ns^2 np^6\) (giving a total of 8 electrons, an octet).


The only exception is Helium (\(He\)), which has a configuration of \(1s^2\) (a duplet).
Quick Tip: The filled octet configuration is the reason why noble gases have the highest ionisation enthalpies in their respective periods.

Let the element be \(X\).

In the +3 oxidation state (\(X^{3+}\)), the configuration is \([Ar] 3d^4\).


This means the \(X^{3+}\) ion has \(18 + 4 = 22\) electrons.


To find the number of electrons in the neutral atom \(X\), we add the 3 electrons that were lost to reach the +3 state:
\(Z = 22 + 3 = 25\).


The element with atomic number 25 is Manganese (\(Mn\)). Its ground state configuration is \([Ar] 3d^5 4s^2\).
Quick Tip: Atomic Number (\(Z\)) = electrons in ion + magnitude of charge.

Lanthanides are the elements from atomic number 58 (Cerium) to 71 (Lutetium).


The general valence shell configuration is approximately \(4f^{1-14} 5d^{0-1} 6s^2\).


The +3 oxidation state is highly stable and is the most characteristic and common oxidation state exhibited by all lanthanides. Some elements also show +2 or +4 states to achieve extra stability (empty, half-filled, or fully-filled f-shells).
Quick Tip: Lanthanides are also known as rare earth elements and show very similar chemical properties due to the lanthanide contraction.

In a coordination compound, the sum of oxidation states of all atoms equals the net charge on the complex.


Carbonyl (\(CO\)) is a neutral ligand; its charge is 0.


Let the oxidation state of Nickel be \(x\).
\(x + 4(0) = 0\).
\(x = 0\).


Therefore, Nickel is in the zero oxidation state in nickel tetracarbonyl.
Quick Tip: Transition metals often show zero oxidation state when bonded with strong-field \(\pi\)-acceptor ligands like \(CO\).

Coordination compounds dissociate into ions only for the part outside the coordination sphere (brackets).


The complex \([Co(NH_3)_5Cl]Cl_2\) dissociates as follows:
\([Co(NH_3)_5Cl]Cl_2 \xrightarrow{aq} [Co(NH_3)_5Cl]^{2+} + 2Cl^-\).


There is one complex cation and two chloride anions.

Total number of ions = \(1 + 2 = 3\).
Quick Tip: The coordination sphere acts as a single entity in solution.

Ionisation isomerism occurs when a ligand within the coordination sphere and a counter-ion outside the sphere exchange places.


The two given complexes have the same overall molecular formula but produce different ions in solution:

1. \([Co(NH_3)_5Br]SO_4 \rightarrow [Co(NH_3)_5Br]^+ + SO_4^{2-}\).

2. \([Co(NH_3)_5SO_4]Br \rightarrow [Co(NH_3)_5SO_4]^+ + Br^-\).


Because they produce different ions, they are ionisation isomers.
Quick Tip: Linkage isomerism requires ambidentate ligands (like \(NO_2, SCN\)).

Vitamin \(B_{12}\), also known as cyanocobalamin, is a coordination compound with a complex ring structure.


The central metal atom in this bio-complex is Cobalt (\(Co\)).


Other important bio-coordination compounds include:

- Haemoglobin (contains Iron).

- Chlorophyll (contains Magnesium).
Quick Tip: Deficiency of Vitamin \(B_{12}\) leads to pernicious anaemia.

Chloroform (\(CHCl_3\)) reacts with acetone (\(CH_3COCH_3\)) in the presence of a base (like \(KOH\)) to undergo an addition reaction.


The \(H\) atom of chloroform adds to the oxygen, and the \(CCl_3\) group adds to the carbonyl carbon.
\(CH_3-CO-CH_3 + CHCl_3 \xrightarrow{KOH} (CH_3)_2C(OH)CCl_3\).


The product formed is 1,1,1-trichloro-2-methylpropan-2-ol, which is commonly known as Chloretone. It is used as a mild hypnotic and sedative.
Quick Tip: Chloretone is also known as "acetone chloroform".

The Wurtz reaction is a classic organic coupling reaction used to prepare higher alkanes from alkyl halides.


Alkyl halides (\(RX\)) react with Metallic Sodium (\(Na\)) in the presence of dry ether to form alkanes containing double the number of carbon atoms as the parent halide.
\(2RX + 2Na \xrightarrow{dry ether} R-R + 2NaX\).


While the question uses the term "reduction", it refers to the standard Wurtz conditions. Among the given options, Sodium in dry ether is the characteristic reagent for this reaction.
Quick Tip: The Wurtz reaction is not suitable for preparing alkanes with odd numbers of carbon atoms, as it would result in a mixture of products.

When ethyl bromide (\(C_2H_5Br\)) is boiled with alcoholic potassium hydroxide (caustic potash), it undergoes a dehydrohalogenation reaction (\(\beta\)-elimination).


A molecule of \(HBr\) is removed from the alkyl halide. The \(Br\) is lost from the \(\alpha\)-carbon and \(H\) is lost from the \(\beta\)-carbon.
\(CH_3-CH_2-Br + KOH(alc.) \xrightarrow{\Delta} CH_2=CH_2 + KBr + H_2O\).


The organic product formed is Ethylene (Ethene).
Quick Tip: Alcoholic \(KOH\) leads to elimination (alkene), while Aqueous \(KOH\) leads to substitution (alcohol).

A mixture of an aryl halide (\(C_6H_5X\)) and an alkyl halide (\(RX\)) reacts with metallic sodium in dry ether to give an alkyl-benzene. This specific modification is called the Wurtz-Fittig reaction.


If both were alkyl halides, it would be the Wurtz reaction.

If both were aryl halides, it would be the Fittig reaction.


Therefore, the given equation represents the Wurtz-Fittig reaction.
Quick Tip: This reaction is a useful way to attach alkyl chains to aromatic rings.

Primary aliphatic amines react with nitrous acid (\(HNO_2\)) to form unstable diazonium salts, which immediately decompose to liberate nitrogen gas and form alcohols.


Ethyl amine (\(C_2H_5NH_2\)) reacts with \(HNO_2\) (typically prepared in situ from \(NaNO_2\) and \(HCl\)):
\(C_2H_5NH_2 + HNO_2 \rightarrow C_2H_5OH + N_2 + H_2O\).


Thus, the reagent is nitrous acid (\(HNO_2\)).
Quick Tip: This reaction is used as a test to distinguish between primary, secondary, and tertiary amines.

Methyl alcohol (\(CH_3OH\)) was historically produced by the destructive distillation of wood.


Because of its origin, it is commonly known as "wood spirit" or "wood alcohol".


It is a highly toxic liquid. Its consumption leads to blindness and even death.
Quick Tip: Ethyl alcohol is often called "grain alcohol".

When alcohol vapours are passed over heated copper at \(573 K\):

- Primary alcohols undergo dehydrogenation to form aldehydes.

- Secondary alcohols undergo dehydrogenation to form ketones.

- Tertiary alcohols do not have \(\alpha\)-hydrogen; instead of dehydrogenation, they undergo dehydration to form alkenes.


For example, \(tert\)-butyl alcohol would yield isobutylene.


Therefore, the alcohol that gives an alkene under these conditions is a tertiary alcohol.
Quick Tip: Dehydrogenation is the removal of \(H_2\), while dehydration is the removal of \(H_2O\).

Phenols react with neutral or aqueous ferric chloride (\(FeCl_3\)) solution to form complex coloured compounds.


Phenol itself gives a deep violet or purple colouration. Other phenols may give blue, green, or red colours.


This is the standard laboratory test for the detection of the phenolic group.


Bromine water reacts with phenol to give a white precipitate of 2,4,6-tribromophenol.
Quick Tip: The colour is due to the formation of a coordination complex between the phenoxide ion and \(Fe^{3+}\).

Ethers have the general structure R-O-R'. They are isomeric with monohydric alcohols.


For a saturated aliphatic ether, the general formula is \(C_nH_{2n+2}O\).

Example: Diethyl ether (\(C_2H_5-O-C_2H_5\)) has formula \(C_4H_{10}O\). Here \(n=4\), so \(2n+2 = 10\).

\(C_nH_{2n}O\) corresponds to aldehydes and ketones.
\(C_nH_{2n}O_2\) corresponds to carboxylic acids and esters.
Quick Tip: Alcohols and ethers are functional isomers.

Tollen's reagent, Fehling's solution, and Schiff's reagent are mild oxidizing agents. They react with aldehydes (like acetaldehyde) but do not react with ketones (like acetone).


A Grignard reagent (\(RMgX\)) is a powerful nucleophile. It undergoes nucleophilic addition to the carbonyl group (\(C=O\)) of both aldehydes and ketones.

- With acetaldehyde, it forms a secondary alcohol after hydrolysis.

- With acetone, it forms a tertiary alcohol after hydrolysis.


Therefore, Grignard reagent reacts easily with both.
Quick Tip: Grignard reagent with formaldehyde (\(HCHO\)) gives a primary alcohol.

The given compound is a ketone: \(CH_3-CH_2-CO-CH_2-CH_3\).


Steps for IUPAC naming:

1. Identify the longest chain containing the carbonyl group. There are 5 carbons, so the parent alkane is pentane.

2. Number the chain such that the carbonyl carbon gets the lowest possible number. From either end, it is at position 3.

3. Replace the '-e' of pentane with '-one'.

4. The name is pentan-3-one or 3-pentanone.


Diethyl ketone is the common name.
Quick Tip: Pentan-2-one and Pentan-3-one are position isomers.

The Cannizzaro reaction is a disproportionation reaction exhibited by aldehydes that do not have any \(\alpha\)-hydrogen atoms.


In the presence of concentrated alkali (\(NaOH\) or \(KOH\)):

- One molecule of the aldehyde is reduced to the corresponding alcohol.

- Another molecule is oxidized to the salt of the corresponding carboxylic acid.


Formaldehyde (\(HCHO\)) and Benzaldehyde (\(C_6H_5CHO\)) do not have \(\alpha\)-hydrogens.
\(2HCHO + conc. NaOH \rightarrow CH_3OH + HCOONa\).


Acetaldehyde (\(CH_3CHO\)) has \(\alpha\)-hydrogens and undergoes Aldol condensation instead.
Quick Tip: Cannizzaro reaction is an example of an auto-redox reaction.

Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes.


Its chemical name is 2,3-dihydroxybutanedioic acid. The structural formula is:
\(HOOC-CH(OH)-CH(OH)-COOH\).


Looking at the options provided on page 30 of the PDF, Structure (C) shows this correct linkage of two carboxylic acid groups and two hydroxyl groups on a four-carbon chain.
Quick Tip: Tartaric acid has two chiral centres and can exist in three stereoisomeric forms: (+), (-), and meso.

Carboxylic acids are stronger acids than carbonic acid (\(H_2CO_3\)).


They react with sodium bicarbonate (\(NaHCO_3\)) or sodium carbonate to liberate carbon dioxide gas. This gas comes out in the form of brisk effervescence.
\(RCOOH + NaHCO_3 \rightarrow RCOONa + H_2O + CO_2 \uparrow\).


Among the given options, acetic acid (\(CH_3COOH\)) is a carboxylic acid. It will react with \(NaHCO_3\) to give effervescence.


Alcohols, alkanes, and alkenes are too weakly acidic to react with bicarbonate.
Quick Tip: The bicarbonate test is used to distinguish carboxylic acids from phenols (except nitrophenols).

The "isopropyl" group refers to the 1-methylethyl group, where the attachment is to the middle carbon of a three-carbon chain: \((CH_3)_2CH-\).


Steps for naming:

1. Structure (A) is n-propylamine.

2. Structure (B) is ethylmethylamine.

3. Structure (C) is \((CH_3)_2CH-NH_2\). Here, the amine group is attached to the isopropyl group. This is Isopropyl amine. Its IUPAC name is propan-2-amine.
Quick Tip: Isopropyl amine is a primary amine because the nitrogen is attached to only one carbon atom.

The Hoffmann Bromamide degradation reaction is used to prepare primary amines containing one carbon atom less than the parent amide.


When acetamide (\(CH_3CONH_2\)) is treated with bromine and an aqueous/ethanolic solution of \(KOH\), methyl amine is produced.
\(CH_3CONH_2 + Br_2 + 4KOH \rightarrow CH_3NH_2 + K_2CO_3 + 2KBr + 2H_2O\).


Wurtz reaction is for alkanes, Friedel-Crafts for alkylation/acylation of aromatic rings, and Kolbe's for phenol to salicylic acid.
Quick Tip: Hoffmann Bromamide reaction is an example of a degradation reaction as the chain length is shortened.

Maltose is a disaccharide commonly known as malt sugar.


It is composed of two units of \(\alpha\)-D-glucose joined by a glycosidic linkage between C1 of one unit and C4 of the other (\(1 \rightarrow 4\) linkage).


On hydrolysis with dilute acids or by the enzyme maltase, one molecule of maltose yields two molecules of D-glucose.
\(C_{12}H_{22}O_{11} + H_2O \rightarrow 2C_6H_{12}O_6\) (Glucose).
Quick Tip: Sucrose yields glucose + fructose; Lactose yields glucose + galactose.

Macromolecules are very large molecules, typically polymers, with high molecular masses (thousands or millions of Daltons).


- DNA (nucleic acid), Starch (polysaccharide), and Insulin (protein) are all biopolymers and fall under the category of macromolecules.


- Palmitate (the salt of palmitic acid) is a saturated fatty acid. It has a relatively small molecular mass (\(C_{16}H_{31}O_2^- \approx 255\) g/mol). It is a component of lipids but is not itself a macromolecule.
Quick Tip: Biomacromolecules include proteins, nucleic acids, and polysaccharides.

A Zwitter ion (dipolar ion) is a molecule that contains both a positive and a negative charge but has a net charge of zero.


This occurs in molecules that have both an acidic group (-COOH) and a basic group (\(-NH_2\)).


Amino acids exist as Zwitter ions. Glycine (\(H_2N-CH_2-COOH\)) undergoes internal proton transfer: the carboxyl group loses a proton and the amino group gains it.
\(H_2N-CH_2-COOH \rightleftharpoons H_3N^+-CH_2-COO^-\).


Simple acids like acetic acid or simple amines like ethylamine cannot form Zwitter ions.
Quick Tip: Due to the Zwitter ionic nature, amino acids are crystalline solids with high melting points and behave like salts.

Antioxidants are substances that prevent the oxidation of food and other materials, thereby preventing spoilage (rancidity).


Citric acid is a common natural antioxidant found in citrus fruits. It acts by scavenging free radicals and chelating metal ions that might otherwise catalyze oxidation reactions.


EDTA is a chelating agent, Sodium nitrite is a preservative (used in cured meats), and Sodium gluconate is a sequestrant.
Quick Tip: Common industrial antioxidants include BHA (Butylated Hydroxyanisole) and BHT.

Riboflavin is a water-soluble vitamin belonging to the B-vitamin group.


Its chemical designation is Vitamin \(B_2\). It is essential for energy production and cellular function.


For reference:

Vitamin \(B_1\) is Thiamine.

Vitamin \(B_6\) is Pyridoxine.

Vitamin \(B_{12}\) is Cyanocobalamin.
Quick Tip: Deficiency of riboflavin causes cheilosis (fissuring at corners of mouth and lips).

Tranquilizers are a class of chemical compounds used for the treatment of stress, and mild or severe mental diseases. They relieve anxiety, irritability, or excitement by inducing a sense of well-being.


Barbiturates are an important class of tranquilizers. Examples include Veronal, Amytal, Nembutal, and Luminal.


Tofranil and Mescaline are antidepressants/hallucinogens. Sulphadiazine is an antibacterial drug (sulpha drug).
Quick Tip: Tranquilizers form an essential component of sleeping pills.