UP Board Class 12 Chemistry Question Paper 2024 (Code 347 GA) Available- Download Here with Solution PDF

Iron (\( Fe \)) belongs to the d-block elements because its valence electrons are present in the d-orbital. The electronic configuration of \( Fe \) is \( [Ar]\, 3d^6 4s^2 \). Quick Tip: d-block elements are also called transition metals and typically have partially filled d-orbitals.

The configuration \( 3d^5, 4s^2 \) corresponds to elements like manganese (\( Mn \)), which shows the maximum oxidation state of +7 due to the loss of all 4s and 3d electrons. Quick Tip: Elements with half-filled or fully filled d-orbitals can exhibit maximum oxidation states.

The salt bridge maintains ionic balance and completes the circuit in a galvanic cell. Removing it stops ion flow, making the cell voltage drop to zero instantly. Quick Tip: A salt bridge prevents charge buildup and ensures the flow of current in a galvanic cell.

The standard hydrogen electrode (\( SHE \)) is assigned a potential of \( 0.0 \) volts by convention. It acts as a reference electrode in electrochemistry. Quick Tip: The standard hydrogen electrode is the primary reference for measuring electrode potentials.

The formula \( K = Ae^{-E_a / RT} \) is the Arrhenius equation, where:
- \( K \): Rate constant,
- \( A \): Pre-exponential factor,
- \( E_a \): Activation energy,
- \( R \): Gas constant,
- \( T \): Temperature. Quick Tip: The Arrhenius equation explains how temperature and activation energy affect reaction rates.

For the reaction \( \frac{1}{2} A \rightarrow 2B \), the rate of reaction can be expressed in terms of the rate of disappearance of \( A \) and the rate of formation of \( B \): \[ -\frac{1}{2} \frac{d[A]}{dt} = \frac{1}{2} \frac{d[B]}{dt}. \]
Rearranging, we get: \[ -\frac{d[A]}{dt} = \frac{1}{2} \frac{d[B]}{dt}. \]

This relation shows that the rate of dissociation of \( A \) is half the rate of formation of \( B \). Quick Tip: In stoichiometry, the rates of reactants and products are inversely proportional to their respective coefficients in the balanced equation.

The resonating structures of aniline (\( C_6H_5NH_2 \)) are as follows:

 Structure 1:  Delocalization of lone pair of electrons from the nitrogen into the benzene ring.

Structure 2, 3, etc.:  Draw the other resonance structures here. Quick Tip: Aniline's resonance structures show delocalization of lone pairs on nitrogen, making it less basic than aliphatic amines.

- Temperature: Increasing the temperature increases the reaction rate by providing reactants with more kinetic energy to overcome the activation energy barrier.
- Concentration: Higher reactant concentration leads to more frequent collisions, increasing the reaction rate according to the rate law. Quick Tip: Use the Arrhenius equation to analyze how temperature affects the reaction rate, and apply the rate law for concentration effects.

- In aqueous solution, \( K_4[Fe(CN)_6] \) dissociates as: \[ K_4[Fe(CN)_6] \rightarrow 4K^+ + [Fe(CN)_6]^{4-}. \]
- Oxidation number of \( Fe \) in \( [Fe(CN)_6]^{4-} \) is \( +2 \): \[ x + (-1 \times 6) = -4 \quad \Rightarrow \quad x = +2. \] Quick Tip: The oxidation state of the central metal ion is calculated by balancing the charge of the complex ion.

- Galvanic Cell: Converts chemical energy into electrical energy. It has a spontaneous reaction.
- Electrolytic Cell: Converts electrical energy into chemical energy. It has a non-spontaneous reaction. Quick Tip: Galvanic cells work spontaneously (e.g., batteries), while electrolytic cells require external energy (e.g., electrolysis).

Moles of ethanol: \[ Moles of ethanol = \frac{Mass}{Molar mass} = \frac{46}{46} = 1 \, mol. \]
Moles of water: \[ Moles of water = \frac{54}{18} = 3 \, mol. \]
Mole fraction of ethanol: \[ Mole fraction of ethanol = \frac{Moles of ethanol}{Total moles} = \frac{1}{1+3} = 0.25. \]
Mole fraction of water: \[ Mole fraction of water = 1 - 0.25 = 0.75. \] Quick Tip: Mole fractions always add up to 1, and they are dimensionless quantities.

Moles of \( Na_2CO_3 \): \[ Moles = \frac{Mass}{Equivalent weight} = \frac{1.325}{53} = 0.025 \, mol. \]
Normality: \[ Normality = \frac{Moles}{Volume (in L)} = \frac{0.025}{0.25} = 0.1 \, N. \] Quick Tip: Normality is the number of gram-equivalents of solute per liter of solution.

1. Used as an antiseptic in low concentrations.
2. Used in the production of plastics like Bakelite.
3. Intermediate in the synthesis of dyes and drugs. Quick Tip: Phenol's versatility makes it crucial in industries ranging from medicine to materials science.

1. Regulate growth and development.
2. Control metabolic processes.
3. Maintain homeostasis in the body. Quick Tip: Hormones act as chemical messengers, coordinating various physiological processes.

Rosenmund Reduction:
In Rosenmund reduction, acid chlorides are reduced to aldehydes using hydrogen gas and palladium catalyst poisoned with barium sulfate: \[ RCOCl + H_2 \xrightarrow{Pd/BaSO_4} RCHO. \]

Reaction of ethyne with water:
Ethyne reacts with water in the presence of \( H_2SO_4 \) and \( HgSO_4 \) to form acetaldehyde: \[ HC \equiv CH + H_2O \xrightarrow{H_2SO_4, HgSO_4} CH_3CHO. \] Quick Tip: Rosenmund reduction is useful for selectively reducing acid chlorides to aldehydes, while ethyne hydration gives aldehydes via Markovnikov's addition.

- Molecularity: The number of reacting species involved in an elementary reaction. It is always a whole number.
- Order: The sum of the powers of the concentration terms in the rate law. It can be fractional or zero.

Velocity equation for zero-order reaction: \[ Rate = k \quad (independent of reactant concentrations). \]

For the reaction \( H_2 + Cl_2 \rightarrow 2HCl \), the rate equation is: \[ Rate = k. \] Quick Tip: Molecularity applies to elementary reactions only, while order is determined experimentally for any reaction.

- Specific resistance (\( \rho \)): The resistance offered by a unit length and unit cross-sectional area of a material. It is given by: \[ \rho = R \cdot \frac{A}{l}, \]
where \( R \) is resistance, \( A \) is cross-sectional area, and \( l \) is the length.

- Conductance (\( G \)): The reciprocal of resistance. It is given by: \[ G = \frac{1}{R}. \] Quick Tip: Specific resistance depends on material properties, while conductance measures the ease of electric flow.

- Reactivity: The bromine atom in bromoethane is more reactive because it is bonded to an sp\(^3\)-hybridized carbon, making the \( C-Br \) bond weaker and more prone to cleavage. In bromobenzene, the bromine is bonded to an sp\(^2\)-hybridized carbon in the benzene ring, stabilizing the bond due to resonance.

Chemical Equation:
The reaction of bromoethane with sodium in dry ether is the Wurtz reaction, forming ethane: \[ 2C_2H_5Br + 2Na \xrightarrow{dry ether} C_2H_6 + 2NaBr. \] Quick Tip: In bromoalkanes, the \( C-Br \) bond is weaker than in bromobenzenes, making them more reactive. The Wurtz reaction is used for alkane synthesis.

- Amines: Amines are organic compounds derived from ammonia (\( NH_3 \)) by replacing one or more hydrogen atoms with alkyl or aryl groups.

Differentiating test: Hinsberg test:
- Primary amines form a soluble sulfonamide.
- Secondary amines form an insoluble sulfonamide.
- Tertiary amines do not react. Quick Tip: Amines are classified as primary, secondary, or tertiary based on the number of alkyl or aryl groups attached to nitrogen.

(x) Reaction of ethanamine with HCl: \[ CH_3CH_2NH_2 + HCl \rightarrow CH_3CH_2NH_3^+Cl^-. \]

(y) Reaction of aniline with \( NaNO_2 \) and dilute HCl: \[ C_6H_5NH_2 + NaNO_2 + 2HCl \xrightarrow{0^\circ C} C_6H_5N_2^+Cl^- + 2H_2O. \] Quick Tip: Primary aromatic amines undergo diazotization to form diazonium salts, while aliphatic amines form ammonium salts with acids.

- d-block elements: Elements in which the last electron enters the d-orbital. Examples: Transition metals like Fe, Cu.
- f-block elements: Elements in which the last electron enters the f-orbital. Examples: Lanthanides and Actinides. Quick Tip: d-block elements show variable oxidation states, while f-block elements are known for their magnetic and spectral properties.

- d-block elements: \( (n-1)d^{1-10}ns^{0-2} \).
- f-block elements: \( (n-2)f^{1-14}(n-1)d^{0-1}ns^2 \). Quick Tip: d-block elements are also called transition elements, while f-block elements include inner transition metals.

(i) Ethanol is heated with sodium bromide and conc. \( H_2SO_4 \): \[ C_2H_5OH + NaBr + H_2SO_4 \rightarrow C_2H_5Br + NaHSO_4 + H_2O. \]


Heating alcohols with sodium halides and acids forms alkyl halides.


(ii) Toluene reacts with \( Cl_2 \) gas in the presence of Fe powder in the dark: \[ C_6H_5CH_3 + Cl_2 \xrightarrow{Fe} C_6H_4ClCH_3 + HCl. \]


In the dark, halogenation of aromatic hydrocarbons occurs at the benzene ring.

(iii) Benzene diazonium chloride reacts with water: \[ C_6H_5N_2^+Cl^- + H_2O \xrightarrow{\Delta} C_6H_5OH + N_2 + HCl. \]


Diazonium salts decompose in water to form phenols.


(iv) 2-Bromopentane is heated with alcoholic \( KOH \): \[ CH_3CH(Br)CH_2CH_2CH_3 \xrightarrow{alc.\,KOH} CH_3CH=CHCH_2CH_3 + HBr. \] Quick Tip: Alcoholic \( KOH \) causes dehydrohalogenation, forming alkenes.

Raoult’s Law:
The relative lowering of vapour pressure is equal to the mole fraction of the solute: \[ P_1 = P_1^0 \cdot (1 - x_2), \]
where \( P_1^0 \) is the vapour pressure of pure solvent, \( P_1 \) is the vapour pressure of solution, and \( x_2 \) is the mole fraction of solute.

Calculation:
- Moles of glucose: \[ Moles of glucose = \frac{25}{180} = 0.1389 \, mol. \]
- Moles of water: \[ Moles of water = \frac{450}{18} = 25 \, mol. \]
- Mole fraction of glucose: \[ x_2 = \frac{Moles of glucose}{Total moles} = \frac{0.1389}{25 + 0.1389} = 0.00554. \]
- Vapour pressure of solution: \[ P_1 = 17.535 \cdot (1 - 0.00554) = 17.435 \, mmHg. \] Quick Tip: Raoult’s law applies to ideal solutions and relates vapour pressure lowering to solute concentration.

Valence Bond Theory (VBT):
- VBT explains the bonding in coordination compounds by considering the hybridization of orbitals on the central metal atom or ion.
- The metal ion provides vacant orbitals to accommodate the lone pairs of electrons donated by ligands, forming coordinate covalent bonds.
- The geometry of the complex depends on the type of hybridization:
- \( sp^3 \): Tetrahedral
- \( dsp^2 \): Square planar
- \( d^2sp^3 \): Octahedral

Demerits of VBT:
1. Fails to explain the color of coordination compounds.
2. Cannot account for the magnetic properties of some complexes.
3. Does not provide a quantitative measure of bond strength or stability. Quick Tip: VBT is useful for explaining the geometry of complexes but is limited in predicting their optical and magnetic properties.

1. Medicinal applications: Cisplatin is used as an anti-cancer drug.
2. Biological importance: Hemoglobin (iron complex) and chlorophyll (magnesium complex) are vital for life processes.
3. Industrial applications: Coordination compounds like \( [Ag(NH_3)_2]^+ \) are used in photography.
4. Analytical chemistry: Complexometric titrations use EDTA as a ligand. Quick Tip: Coordination compounds play key roles in medicine, biology, industry, and analytical chemistry.

Amino Acids:
- Building blocks of proteins, containing an amino group (\(-NH_2\)) and a carboxyl group (\(-COOH\)).
- Essential amino acids must be obtained from the diet.
- Functions: Protein synthesis, enzyme activity, and metabolism regulation.

Nucleic Acids:
- DNA and RNA are polymers of nucleotides, composed of a sugar, phosphate group, and nitrogenous base.
- DNA stores genetic information, while RNA is involved in protein synthesis. Quick Tip: Amino acids are essential for protein structure, while nucleic acids are carriers of genetic information.

(i) Vitamin A:
- Source: Carrots, sweet potatoes, spinach.
- Deficiency Disease: Night blindness.

(ii) Vitamin C:
- Source: Citrus fruits, tomatoes, strawberries.
- Deficiency Disease: Scurvy (bleeding gums, weakened immunity).

(iii) Vitamin D:
- Source: Sunlight, fish liver oil, fortified milk.
- Deficiency Disease: Rickets (in children) and osteomalacia (in adults).

(iv) Vitamin E:
- Source: Nuts, seeds, green leafy vegetables.
- Deficiency Disease: Neurological problems and muscle weakness.

(v) Vitamin K:
- Source: Green leafy vegetables, broccoli, soybean oil.
- Deficiency Disease: Delayed blood clotting and excessive bleeding. Quick Tip: Vitamins are essential nutrients required in small amounts to prevent deficiency diseases and maintain health.

- Compound \( A \): Ethanoic acid (\( CH_3COOH \))
- Compound \( B \): Ethanol (\( CH_3CH_2OH \))
- Compound \( C \): Ethanoic anhydride (\( (CH_3CO)_2O \))

Chemical equations:

1. Hydrolysis of \( C_4H_8O_2 \) (ethyl acetate): \[ CH_3COOC_2H_5 + H_2O \xrightarrow{H_2SO_4} CH_3COOH + C_2H_5OH \]

2. Oxidation of ethanol (\( B \)): \[ C_2H_5OH + [O] \xrightarrow{H_2CrO_4} CH_3COOH \]

3. Formation of acid anhydride (\( C \)): \[ 2CH_3COOH \xrightarrow{P_2O_5} (CH_3CO)_2O + H_2O \]

4. Hydrolysis of acid anhydride (\( C \)): \[ (CH_3CO)_2O + H_2O \rightarrow 2CH_3COOH \] Quick Tip: Carboxylic acids form anhydrides when heated with dehydrating agents like \( P_2O_5 \), and the process is reversible via hydrolysis.

(i) Benzene from benzoic acid: \[ C_6H_5COOH + NaOH \xrightarrow{\Delta} C_6H_6 + Na_2CO_3 \]


Decarboxylation of carboxylic acids with soda lime produces hydrocarbons.

(ii) Phthalimide from phthalic acid: \[ C_6H_4(COOH)_2 \xrightarrow{NH_3, \Delta} C_6H_4(CO)NH \]


Heating phthalic acid with ammonia produces phthalimide via dehydration.


(iii) \( m \)-Nitrobenzaldehyde from benzaldehyde: \[ C_6H_5CHO + HNO_3 \xrightarrow{Conc. H_2SO_4} C_6H_4(NO_2)CHO \]


Nitration of benzaldehyde selectively produces nitro derivatives at meta positions.


(iv) Benzaldehyde from benzene: \[ C_6H_6 + CO + HCl \xrightarrow{AlCl_3} C_6H_5CHO \]


The Gattermann-Koch reaction is used to form benzaldehyde from benzene.


(v) Silver mirror from \( C_6H_5CHO \): \[ C_6H_5CHO + 2[Ag(NH_3)_2]^+ + 3OH^- \rightarrow C_6H_5COOH + 2Ag + 4NH_3 + H_2O \] Quick Tip: The silver mirror test is a qualitative test for aldehydes using Tollens' reagent.

Phenol from cumene: \[ C_6H_5CH(CH_3)_2 + [O] \rightarrow C_6H_5OH + CH_3COCH_3 \]

(i) Reaction of phenol with zinc powder: \[ C_6H_5OH + Zn \xrightarrow{\Delta} C_6H_6 + ZnO \]


Heating phenol with zinc powder reduces it to benzene.


(ii) Reaction of phenol with conc. \( HNO_3 \): \[ C_6H_5OH + HNO_3 \xrightarrow{H_2SO_4} C_6H_2(NO_2)_3OH \]


Phenol undergoes nitration to form picric acid (\( 2,4,6 \)-trinitrophenol) with concentrated nitric acid.


(iii) Reaction of phenol with bromine water: \[ C_6H_5OH + 3Br_2 \xrightarrow{aq.} C_6H_2Br_3OH + 3HBr \]


Phenol reacts with bromine water to form a white precipitate of tribromophenol.