Chemistry: Full Syllabus Mock Test 2
Time: 3 Hours | Maximum Marks: 70
- The question paper is divided into four sections: A, B, C, and D.
- Section A: Q. No. 1 contains 10 multiple-choice questions carrying 1 mark each. Q. No. 2 contains 8 very short answer type questions carrying 1 mark each.
- Section B: Q. No. 3 to Q. No. 14 are short answer type questions carrying 2 marks each. Attempt any 8 questions.
- Section C: Q. No. 15 to Q. No. 26 are short answer type questions carrying 3 marks each. Attempt any 8 questions.
- Section D: Q. No. 27 to Q. No. 31 are long answer type questions carrying 4 marks each. Attempt any 3 questions.
- Use of logarithmic tables is allowed. Use of calculator is not allowed.
- Figures to the right indicate full marks.
SECTION A
Q1. Select and write the most appropriate answer from the given alternatives: [10 Marks]
-
The coordination number of atoms in a body-centered cubic (BCC) crystal lattice is:
(A) 4(B) 6(C) 8(D) 12
-
The osmotic pressure ($\pi$) of a dilute solution is given by the equation:
(A) $\pi = P_0 X_2$(B) $\pi = CRT$(C) $\pi = K_b m$(D) $\pi = \frac{RT}{C}$
-
Which of the following conditions represents a system at chemical equilibrium?
(A) $\Delta G > 0$(B) $\Delta G < 0$(C) $\Delta G = 0$(D) $\Delta S = 0$
-
The geometry of Xenon hexafluoride ($XeF_6$) is:
(A) Octahedral(B) Distorted octahedral(C) Square planar(D) Trigonal bipyramidal
-
For a reaction to have its order equal to its molecularity, the reaction must be:
(A) Pseudo-first order(B) Complex(C) Elementary(D) Zero order
-
The primary cause of the Lanthanoid contraction is:
(A) Poor shielding of 4f electrons(B) Effective shielding of 5d electrons(C) Decrease in nuclear charge(D) Increase in atomic mass
-
Which of the following compounds gives a positive carbylamine test?
(A) $CH_3-NH-CH_3$(B) $(CH_3)_3N$(C) $C_6H_5NH_2$(D) $C_6H_5-NH-CH_3$
-
The product formed when methyl bromide reacts with sodium metal in dry ether is:
(A) Methane(B) Ethane(C) Propane(D) Ethene
-
In an aqueous solution, the most basic amine among the following is:
(A) $CH_3NH_2$(B) $(CH_3)_2NH$(C) $(CH_3)_3N$(D) $NH_3$
-
Which of the following represents a "Design for degradation" principle in Green Chemistry?
(A) Use of PVC(B) Use of biodegradable polymers(C) Use of toxic solvents(D) Atom economy of 50%
Q2. Answer the following questions in one sentence: [8 Marks]
- Define: Ebullioscopic constant.
- What is meant by an isotonic solution?
- Write the formula to calculate the Effective Atomic Number (EAN).
- Name the catalyst used in the Contact Process for the manufacture of $H_2SO_4$.
- Give the IUPAC name of acetic acid.
- Define: Specific conductance (conductivity).
- What is vulcanization of rubber?
- Write the formula for calculating Percentage Atom Economy.
SECTION B
Attempt any EIGHT of the following questions: [16 Marks]
- Distinguish between Schottky and Frenkel defects. (Any 2 points).
- State Faraday's first law of electrolysis and write its mathematical equation.
- What is the action of $PCl_5$ on ethanol? Write the balanced chemical equation.
- Explain why Hydrogen Fluoride (HF) is a liquid at room temperature while Hydrogen Chloride (HCl) is a gas.
- Write the chemical reaction for Gabriel phthalimide synthesis to prepare a primary amine.
- Distinguish between DNA and RNA. (Any 2 points).
- Define geometric isomerism. Draw the cis and trans isomers of $[Pt(NH_3)_2Cl_2]$.
- Write the Nernst equation for the cell reaction: $aA + bB \rightarrow cC + dD$ at 298 K.
- State any two uses of Helium gas.
- What are interstitial compounds? Give one example.
- Write a short note on the Clemmensen reduction.
- Differentiate between thermoplastic and thermosetting polymers. (Any 2 points).
SECTION C
Attempt any EIGHT of the following questions: [24 Marks]
- Derive the relationship between half-life ($t_{1/2}$) and the rate constant ($k$) for a first-order reaction.
- Describe the $S_N1$ mechanism for the alkaline hydrolysis of tert-butyl bromide.
- Explain the Aldol condensation of acetaldehyde with a chemical equation.
- Explain the Sol-Gel process for the synthesis of nanomaterials.
- Describe the preparation of Potassium Dichromate ($K_2Cr_2O_7$) from chromite ore. (Write only the chemical equations).
- On the basis of Valence Bond Theory (VBT), explain the geometry and magnetic property of the $[CoF_6]^{3-}$ complex. (Atomic number of Co = 27).
- Calculate the standard enthalpy of formation of $CH_4(g)$ if standard enthalpies of combustion of Carbon (graphite), $H_2(g)$, and $CH_4(g)$ are -393.5 kJ/mol, -285.8 kJ/mol, and -890.3 kJ/mol respectively.
- Explain the relative basicity of primary, secondary, and tertiary methylamines in an aqueous solution.
- What is a peptide bond? Write a chemical equation to show its formation between two molecules of glycine.
- Explain Williamson synthesis for the preparation of ethers with a suitable example.
- Describe the construction and working of the Standard Hydrogen Electrode (SHE).
- An element has a body-centered cubic (BCC) structure with a cell edge of 288 pm. The density of the element is 7.2 g/cm³. Calculate the molar mass of the element. ($N_A = 6.022 \times 10^{23} \text{ mol}^{-1}$).
SECTION D
Attempt any THREE of the following questions: [12 Marks]
- (a) Derive the expression for the maximum work ($W_{max}$) done by a system during an isothermal and reversible expansion of an ideal gas. [3 Marks]
(b) What is meant by a zero-order reaction? [1 Mark] - (a) Describe the $S_N2$ mechanism for the alkaline hydrolysis of methyl bromide. [3 Marks]
(b) What are copolymers? Give one example. [1 Mark] - (a) Distinguish between Lanthanoids and Actinoids. (Any 3 points). [3 Marks]
(b) What is the oxidation state of Manganese in $KMnO_4$? [1 Mark] - (a) Describe the preparation of phenol from cumene with necessary chemical equations. [3 Marks]
(b) Write the structural formula of EDTA. [1 Mark] - (a) A solution containing 0.5126 g of naphthalene (molar mass 128 g/mol) in 50 g of carbon tetrachloride yields a boiling point elevation of 0.402 K. Calculate the molal elevation constant ($K_b$) of carbon tetrachloride. [2 Marks]
(b) Derive the integrated rate law equation for a first-order reaction. [2 Marks]
Solutions & Marking Scheme
Maximum Marks: 70
SECTION A [18 Marks]
Q1. Multiple Choice Answers [10 Marks]:
1. (C) 8 [1 M. The central atom touches 8 corner atoms]
2. (B) $\pi = CRT$ [1 M]
3. (C) $\Delta G = 0$ [1 M]
4. (B) Distorted octahedral [1 M]
5. (C) Elementary [1 M. Complex reactions have varying orders]
6. (A) Poor shielding of 4f electrons [1 M]
7. (C) $C_6H_5NH_2$ [1 M. Carbylamine is for primary amines only]
8. (B) Ethane [1 M. Wurtz coupling of two methyl groups]
9. (B) $(CH_3)_2NH$ [1 M. $2^\circ > 1^\circ > 3^\circ$ in aqueous]
10. (B) Use of biodegradable polymers [1 M]
Q2. Very Short Answers [8 Marks]:
1. Ebullioscopic constant ($K_b$): The elevation in boiling point produced when 1 mole of a non-volatile solute is dissolved in 1 kg of solvent. [1 M]
2. Isotonic solution: Two or more solutions having the same osmotic pressure at a given temperature. [1 M]
3. EAN formula: EAN = $Z - X + Y$ (where Z=atomic no, X=oxidation state, Y=electrons donated by ligands). [1 M]
4. Contact Process Catalyst: Vanadium pentoxide ($V_2O_5$) or Platinized asbestos. [1 M]
5. IUPAC of Acetic acid: Ethanoic acid. [1 M]
6. Specific conductance ($\kappa$): It is the reciprocal of specific resistance (resistivity). [1 M]
7. Vulcanization: The process of heating natural rubber with sulfur to improve its physical properties by forming cross-links. [1 M]
8. Percentage Atom Economy: (Formula weight of desired product / Sum of formula weights of all reactants) $\times 100$. [1 M]
SECTION B [16 Marks] (Attempt Any 8)
Q3. Schottky vs Frenkel Defect:
| Schottky Defect | Frenkel Defect |
|---|---|
| Equal number of cations and anions are missing from lattice. | An ion leaves its regular site and occupies an interstitial site. |
| Density of the crystal decreases. | Density remains unchanged. |
[1 M for each point. Total 2 M]
Q4. Faraday's First Law:
Statement: The mass of any substance deposited or liberated at an electrode is directly proportional to the quantity of electricity passed through the electrolyte. [1 M]
Equation: $W = Z \cdot Q$ OR $W = Z \cdot I \cdot t$. [1 M]
Q5. Action of $PCl_5$ on Ethanol:
Ethanol reacts with Phosphorus pentachloride to form Ethyl chloride, phosphoryl chloride, and hydrogen chloride. [1 M]
$CH_3CH_2OH + PCl_5 \rightarrow CH_3CH_2Cl + POCl_3 + HCl$ [1 M]
Q6. HF (liquid) vs HCl (gas):
Fluorine is highly electronegative and very small. HF molecules form strong intermolecular hydrogen bonds, associating them into a liquid. [1 M]
Chlorine is larger and less electronegative, so HCl molecules only have weak van der Waals forces, making it a gas. [1 M]
Q7. Gabriel Phthalimide Reaction:
Phthalimide $\xrightarrow{\text{alc. KOH}}$ Potassium phthalimide $\xrightarrow{R-X}$ N-alkyl phthalimide $\xrightarrow{NaOH/H_2O}$ Primary Amine ($R-NH_2$) + Sodium phthalate. [2 M for logical sequence or equations]
Q8. DNA vs RNA:
- DNA contains 2-deoxyribose sugar; RNA contains ribose sugar.
- DNA contains Thymine; RNA contains Uracil.
[1 M for each point. Total 2 M]
Q9. Geometric Isomerism & $[Pt(NH_3)_2Cl_2]$:
Isomerism due to different spatial arrangements of ligands around the central metal atom. [1 M]
Cis: Similar ligands on adjacent adjacent corners. Trans: Similar ligands on opposite corners. [1 M for drawing both structures]
Q10. Nernst Equation:
$E_{cell} = E^\circ_{cell} - \frac{2.303 RT}{nF} \log_{10} \frac{[C]^c [D]^d}{[A]^a [B]^b}$ [2 M for correct equation]
Q11. Uses of Helium:
- Used for filling weather balloons. [1 M]
- Used as a diluent for oxygen in deep-sea diving to prevent 'bends'. [1 M]
Q12. Interstitial Compounds:
Compounds formed when small atoms (H, C, N) get trapped in the empty spaces (interstices) of the crystal lattice of transition metals. [1 M]
Example: Steel, Titanium carbide ($TiC$). [1 M]
Q13. Clemmensen Reduction:
Carbonyl group of aldehydes/ketones is reduced to methylene group ($-CH_2-$) by heating with Zinc amalgam ($Zn-Hg$) and conc. HCl. [1 M]
$CH_3COCH_3 + 4[H] \xrightarrow{Zn-Hg / \text{conc. } HCl} CH_3CH_2CH_3 + H_2O$ [1 M]
Q14. Thermoplastic vs Thermosetting:
- Thermoplastic: Soften on heating, harden on cooling (reversible). Linear chains.
- Thermosetting: Hard and infusible on heating (irreversible). Heavily cross-linked.
[1 M for each point. Total 2 M]
SECTION C [24 Marks] (Attempt Any 8)
Q15. Half-life Derivation ($t_{1/2}$):
$k = \frac{2.303}{t} \log\frac{[A]_0}{[A]_t}$. At $t = t_{1/2}$, $[A]_t = \frac{[A]_0}{2}$. [1 M]
$k = \frac{2.303}{t_{1/2}} \log(2)$. [1 M]
Since $\log 2 = 0.3010 \implies t_{1/2} = \frac{0.693}{k}$. [1 M]
Q16. $S_N1$ Mechanism:
Two-step mechanism. Rate depends only on substrate $[(CH_3)_3C-Br]$. [1 M]
Step 1 (Slow): Cleavage of C-Br to form planar tertiary carbocation $(CH_3)_3C^+$. [1 M]
Step 2 (Fast): Nucleophile $OH^-$ attacks from front or back, leading to Racemization. [1 M]
Q17. Aldol Condensation:
Two molecules of acetaldehyde (with $\alpha$-H) react in dil. alkali. [1 M]
$2CH_3CHO \xrightarrow{\text{dil. NaOH}} CH_3-CH(OH)-CH_2-CHO$ (Acetaldol) [1 M]
Acetaldol $\xrightarrow{\Delta, -H_2O} CH_3-CH=CH-CHO$ (Crotonaldehyde) [1 M]
Q18. Sol-Gel Process:
- Hydrolysis: Precursors form a colloidal solution (Sol). [1 M]
- Polycondensation: Particles link to form a 3D network enclosing liquid (Gel). [1 M]
- Drying/Calcination: Liquid removed, heated to form dense nanomaterials. [1 M]
Q19. Preparation of $K_2Cr_2O_7$:
1. $4FeCr_2O_4 + 8Na_2CO_3 + 7O_2 \rightarrow 8Na_2CrO_4 + 2Fe_2O_3 + 8CO_2$ [1 M]
2. $2Na_2CrO_4 + H_2SO_4 \rightarrow Na_2Cr_2O_7 + Na_2SO_4 + H_2O$ [1 M]
3. $Na_2Cr_2O_7 + 2KCl \rightarrow K_2Cr_2O_7 \downarrow + 2NaCl$ [1 M]
Q20. VBT for $[CoF_6]^{3-}$:
$Co^{3+}$ is $3d^6$. $F^-$ is a weak field ligand, no pairing occurs (4 unpaired electrons). [1 M]
Uses outer orbitals (one 4s, three 4p, two 4d) $\rightarrow$ $sp^3d^2$ hybridization $\rightarrow$ Octahedral. [1 M]
Since it has 4 unpaired electrons, it is Paramagnetic. [1 M]
Q21. Enthalpy Numerical:
Target: $C(s) + 2H_2(g) \rightarrow CH_4(g)$
$\Delta_f H^\circ = \Delta H_c(C) + 2\Delta H_c(H_2) - \Delta H_c(CH_4)$ [1 M]
$\Delta_f H^\circ = (-393.5) + 2(-285.8) - (-890.3)$ [1 M]
$\Delta_f H^\circ = -965.1 + 890.3 = -74.8 \text{ kJ/mol}$. [1 M]
Q22. Basicity of Amines (Aqueous):
Order: $(CH_3)_2NH > CH_3NH_2 > (CH_3)_3N$. [1 M]
It is a balance of three factors: [1 M]
- +I effect of methyl groups (favors $3^\circ$).
- Hydration/Solvation of protonated ion via H-bonds (favors $1^\circ$).
- Steric hindrance (decreases basicity of $3^\circ$).
The balance makes $2^\circ$ the most basic. [1 M]
Q23. Peptide Bond:
An amide linkage ($-CO-NH-$) formed between the $-COOH$ group of one amino acid and the $-NH_2$ group of another with the loss of water. [1 M]
$H_2N-CH_2-COOH + H_2N-CH_2-COOH \xrightarrow{-H_2O}$ [1 M]
$H_2N-CH_2-CO-NH-CH_2-COOH$ (Glycylglycine) [1 M]
Q24. Williamson Synthesis:
Reaction of alkyl halide with sodium alkoxide to form ethers via $S_N2$ mechanism. [1.5 M]
$C_2H_5-Br + CH_3-O^-Na^+ \rightarrow C_2H_5-O-CH_3 + NaBr$ [1.5 M]
Q25. Standard Hydrogen Electrode (SHE):
Construction: Pt wire attached to Pt foil coated with Pt black, immersed in $1 \text{ M } H^+$ solution. Pure $H_2$ gas at 1 atm is bubbled. [1.5 M]
Working: It acts as a reference. Its standard potential is exactly 0.00 V. Reaction: $2H^+ + 2e^- \rightleftharpoons H_2(g)$. [1.5 M]
Q26. Density Numerical:
BCC $\implies z=2$. $a = 288 \text{ pm} = 2.88 \times 10^{-8} \text{ cm}$. $\rho = 7.2$. [1 M]
$M = \frac{\rho \cdot a^3 \cdot N_A}{z} = \frac{7.2 \times (2.88 \times 10^{-8})^3 \times 6.022 \times 10^{23}}{2}$ [1 M]
$M = \frac{1035.5}{2} = 51.77 \text{ g/mol}$. [1 M]
SECTION D [12 Marks] (Attempt Any 3)
Q27. (a) $W_{max}$ Derivation [3 Marks] (b) Zero-order [1 Mark]
(a) $dW = -P_{ex} dV$. For reversible, $P_{ex} = P - dP$. So $dW = -P dV$. [1 M]
$W_{max} = -\int_{V_1}^{V_2} P \, dV = -\int_{V_1}^{V_2} \frac{nRT}{V} dV$. [1 M]
$W_{max} = -nRT \ln(V_2/V_1) = -2.303 nRT \log_{10}(V_2/V_1)$. [1 M]
(b) A reaction whose rate is independent of the reactant concentration. [1 M]
Q28. (a) $S_N2$ Mechanism [3 Marks] (b) Copolymers [1 Mark]
(a) Single-step concerted process. $CH_3Br + OH^- \rightarrow CH_3OH + Br^-$. [1 M]
$OH^-$ attacks from back, forming pentacoordinate transition state. [1 M]
Results in 100% Walden inversion. [1 M]
(b) Polymers made from two or more different monomers (e.g., Buna-S). [1 M]
Q29. (a) Lanthanoids vs Actinoids [3 Marks] (b) Mn Oxidation State [1 Mark]
(a) [1 M each]
1. Filling of 4f vs 5f.
2. Most are non-radioactive vs All are radioactive.
3. Show limited oxidation (+3) vs show higher variable states (+3 to +7).
(b) $+7$. [1 M]
Q30. (a) Phenol from Cumene [3 Marks] (b) EDTA [1 Mark]
(a) Cumene + $O_2 \xrightarrow{\text{Co-naph}} $ Cumene hydroperoxide. [1.5 M]
Cumene hydroperoxide $\xrightarrow{H^+}$ Phenol + Acetone. [1.5 M]
(b) Ethylenediaminetetraacetate. Contains 2 N and 4 O donor atoms. [1 M]
Q31. (a) Boiling point Elevation [2 Marks] (b) First Order Derivation [2 Marks]
(a) $K_b = \frac{M_2 \cdot \Delta T_b \cdot W_1}{1000 \cdot W_2} = \frac{128 \times 0.402 \times 50}{1000 \times 0.5126}$. [1 M]
$K_b = 5.019 \text{ K kg mol}^{-1}$. [1 M]
(b) Rate $= -\frac{d[A]}{dt} = k[A] \implies \frac{d[A]}{[A]} = -k \cdot dt$. [1 M]
Integrate: $\ln[A]_t - \ln[A]_0 = -kt \implies k = \frac{2.303}{t} \log_{10} \frac{[A]_0}{[A]_t}$. [1 M]
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