XI Chemistry

SECTION “A” (MCQs – Multiple Choice Questions)

NOTE: Attempt all questions from this Section.

Q.1. Choose the correct answer for each from the given options. (17 Marks)

i. When gaseous anions and cations are brought closer, the energy involved is

• Electron affinity
• Lattice Energy
• Ionization Energy
• Electro Negativity

ii. The molecules which 64gm SO contains are

• 1.02 x 10(23)
• 2.04 x 10(23)
• 3.06 x 10(23)
• 6.02 x 10(23)

iii. Faraday’s experiment indicates, the existence of

• Electron
• Proton
• X-rays
• Positron

iv. The value of “Kc” is independent of

• Initial Concentration of reactants
• Volume
• Catalyst
• Pressure

v. Cabon dioxide (CO₂) molecule has zero dipole moment because its structure is

• Linear
• Tetrahedron
• Angular
• Triangular

vi. The Molecular Mass of Na₂CO₃  is

• 100 a.m.u
• 102 a.m.u
• 104 a.m.u
• 106 a.m.u

vii. Bohr’s model of atom is contradicted by

• Rutherford’s Atomic Model
• Heisenberg’s Uncertainty Principle
• Pauli’s exclusion Principle
• Plank’s quantum Theory

viii. The bond distance between Carbon-Carbon Single bond (C-C) is

• 1.54 A°
• 1.24 A°
• 1.34 A°
• 1.20 A°

ix. The integar part of logarithm is called

• Power
• Characteristic
• Mantissa
• Base

x. The bonds present in one molecule of ethane (C₂H₄) are

• Four Sigma two pi
• Two Sigma four pi
• Five Sigma one pi
• Five pi one Sigma

xi. If pH of a Solution is zero, the nature of solution will be

• Acidic
• Neutral
• Basic
• Amphoteric

xii. Which of the compound has Sp(2) hybridization

• NH₃
• C₂H₂
• C₂H₄
• H₂O

xiii. In hydrogen halides, which of the following possess the largest ionic character?

• HF
• HI
• HCl
• HBr

xiv. Which atomic orbital is always involved in sigma bonding?

• s-Orbital
• p-Orbital
• d-Orbital
• t-Orbital

xv. The colour of light depends upon its

• Wave length
• Velocity
• Source
• None

xvi. The rate of diffusion of C₃H₈ and CO₂ are the same because

• They are gases
• Both Contain Carbon
• Their Molecular Mass are same
• C₃H₈ is an Organic Compound

xvii. The molecular formula of Vitamin “C” is C₆H₈O₆. Its empirical formula is

• C₂H₃O₂
• C₃H₄O₃
• CH₂O
• CHO₂

SECTION “B” – (Short Answer Questions)

Q.2. Answer any TEN questions from this Section. All questions carry equal marks. The answer to each questions should not exceed 6-8 lines. (40 Marks)

i. Define the following terms

• Atomic Number
• Empirical Formula
• Molecular Formula
• Atomic Mass
• Significant Figures
• Mole
• Extensive Properties
• Intensive Properties
• Avogadro’s Number
• Limiting Reactant
• Molar Volume

ii. Describe Rutherford’s Atomic Model and state its defects.

OR

Write the postulates of Bohr’s Atomic Theory.

OR

Derive an expression for the energy of an electron in nth orbit.

OR

Bohr’s radius is 0.529°A. Find the radius of 2nd orbit of hydrogen atom.

iii. Define Ionic bond. Explain the formation of ionic bond with the example of Sodium Chloride and give its properties.

OR

What do you understand by the ionic character of a covalent bond with one example?

OR

Define Coordinate Covalent bond and explain it with the formation of (NH⁺₄)

iv. An organic compound producing air pollution contains 8.73% carbon 77.45% chlorine and 13.82% fluorine; find the molecular formula of the compound if its molecular mass is 137.5. (Atomic Masses: C = 12, Cl = 35.5, F = 19)

OR

A 500cm(3) vessel contains 2gm of He and 8gm of CH₄. What is the total pressure of the mixture of these gases at -3°C. (Atomic Masses: He = 4, C = 12, H = 1)

v. Give the main postulates of Kinetic Molecular Theory of Gases.

OR

State the following Gas Laws.

• Boyle’s Law
• Charle’s Law
• Graham’s Law
• Dalton’s Law of Partial Pressure
• Avogadro’s Law

vi. Write the electronic configuration for the ground state Na (Za = 11) and Mg⁺(2) (Z = 12).

OR

Calculate the wave number of radiation emitted in Lyman series when electron jumps from 2nd to 1st orbit.

vii. Give scientific reasons for the following

a. The rates of diffusion of CO₂ and C₃H₈ gases are the same.
b. FeSO₄.7H₂O and ZnSO₄. 7H₂O are isomorphous.
c. Graphite is very soft where as diamond is very hard.
d. The boiling point of a liquid remains constant although heat is continuously supplied to the liquid.
e. A negative catalyst decreases the rate of reaction.
f. A falling drop of a liquid is always spherical.
g. Ionization potential of oxygen is smaller than that of Nitrogen.
h. Evaporation is a cooling process.
i. Honey is more viscous than water.
j. Zinc dust when reacted with HCl produces hydrogen at a faster rate than a big piece of Zinc.

viii. The equilibrium constant for the reaction N₂(g) + O₂(g) ↔ 2NO(g) at 2000°C is the initial concentration of N₂ and O₂ are 10 moles/dm(3).

OR

Find the molarity of 0.5gm of NaOH in 250cm(3) of aqueous solution.

OR

The solubility of AgCl at 25°C is 1.4 x 10(-3) gm/dm(3). What is its solubility product?

OR

600J of heat was given to a gas at 1.01 x 10⁵ N/m(2) pressure. The initial energy was increased by 300 J; find the increase in volume.

ix. A 100 cm(3) gas cylinder filled with chlorine under 160 torr pressure is connected by stop-cock with another cylinder of 400 cm(3) filled with nitrogen under pressure of 200 torr. What will be the total pressure when stop cock is opened?

OR

Calculate the mass of ZnSO₄, the volume of H₂ and the number of molecules of H₂ which will be produced by reacting 163.5gm of Zn with H₂SO₄, at S.T.P. (Atomic Masses: Zn = 65.4, S = 32, O = 16, H = 1).

x. Explain Evaporation in liquids and Deformity in solids in terms of the Kinetic Molecular Theory.

OR

Differentiate between Crytalline solids and amorphous Solids.

OR

Differentiate between Isomorphism and polymorphism.

OR

What is an Ideal gas? What are the cause of deviation of the real gases from the ideal behaviour?

OR

Determine the General Gas Equation from the gas laws.

xi. What are Cathode Rays? How are they produced? Write down five properties of Cathode Rays along with their experimental proofs.

OR

What is the relationship between X-Rays and Atomic Number

OR

What is Radioactivity? Describe the experiment to distinguish the three types of radio active radiations.

OR

Write down five properties of each Alpha (α), Beta (β), Gamma (γ) rays.

xii. In a reaction A + B ↔ 2C, 7 moles/dm(3) of B were mixed and allowed to attain equilibrium. If Kc = 2.25; find out the concentration of A, B and C at equilibrium.

OR

Will PbCrO₄ precipitate from a solution mixing 200cm(3) of 2.5 x 10⁻⁴ M Pb(NO₃) and 600cm(3) of 1.5 x 10⁻⁸ M K₂CrO₄?

xiii. State the First Law of Thermodynamics and Derive the Equations:

a. ∆H = ∆E = P∆V
b. Qp = ∆H
c. ∆E = Qv

OR

State and explain Hess’s Law of Constant Heat Summation.

OR

Give unit cell of a cubic or orthorhombic system.

xiv. What do you understand the term Hybridization? Discuss Sp(3), Sp(2) and Sp hybridization with examples.

OR

Draw the S-orbital and p-orbital.

OR

Write down the names of the spectral lines of hydrogen atom.

OR

Write down the values of all the four quantum numbers for each of the two electrons of helium atom.

xv. Write short notes on following

• Viscosity
• Electron Affinity
• Common Ion Effect
• Neutralization
• Ionization Potential
• Hydrolysis
• Electronegativity
• Surface Tension
• Hydration
• Buffer Solution
• Vapour Pressure

SECTION “C” – (Detailed Answer Questions)

(28 Marks)

Q.3. (a) Write short notes on the following.

• Hydrogen Bonding
• pH
• Concentration of Solution and its Various Units
• Common Ion Effect
• Plank’s Quantum Theory
• Molarity
• Arrhenius Theory of Ionization
• Heat of Formation

Q.3. (b) Define Rate of Reaction, describe the methods to dormine the rate of reaction and also describe the factors on which the rate of reaction depends?

OR

Differentiate between the following.

• Neutral Radioactivity and Artificial Radioactivity
• Principal Quantum Number and Azimuthal Quantum Number
• Orbit and Orbital
• Line Spectrum and Continuous Spectrum
• Activation Energy and Threshold Energy
• Rate of Reaction and Rate Constant
• Positive Catalyst and Negative Catalyst

Q.3. (c) Describe the following rules of electronic configuration.

i. Pauli’s Exclusion Principle
ii. Aufbau Principle
iii. (n + 1) Rule
iv. Hund’s Rule of Maximum Multiplicity

Q.4. (a) For the Chemical reaction F₂ + 2CIO₂ → 2FCIO₂, Calculate the rate constant when initial concentration of F₂ is 0.1 mol/dm(3), of ClO₂ is 0.01 mol/dm(3) and the rate of reaction is 1.2 x 10(-3) mol/dm(3) sec.

Q.4. (b) What do you understand by the term Electrode Potential? How is the Electrode Potential of Zinc and Copper discovered?

OR

Define solubility product and give its examples and applications.

Q.4. (c) Write down the points of Electron Pair Repulsion Theory and Hybrid Orbital anode. Describe the shapes and structures of CH₃, BeCl₂, H₂O and NH₃ on the basis of Electron Pair Repulsion Theory.

Q.5. (a) What is Dipole Moment? Explain the shapes of CO₂ and H₂O with the help of Dipole Moment.

OR

State Le-Chatlier’s Principles. Apply the Principle on Haber’s Process in terms of pressure and temperature for the maximum yield of NH₃.
N₂(g) + 3H₂(g) ↔ 2NH₃(g) + Heat

Q.5. (b) State the Law of Mass Action. Derive the equilibrium. Constant Kc for reaction nA + nB ↔ nC = yD. Apply the Law of Mass Action on Contact Process to derive its equilibrium expression.

2SO₂(g) + O₂(g) ↔ 2SO₃(g)

Q.5. (c) Differentiate between the following.

• Sp(3) – Hybridization and Sp(2) – Hybridization
• Atomic Orbital and Molecular Orbital
• Valence Bond Theory and Molecular Orbital Theory
• Polar Covalent Bond and Non-Polar Covalent Bond
• Sigma Bond and Pi Bond
• Exothermic Reactions and Endothermic Reactions.