1st year Chemistry Guess paper

[Tanha Karim]

CHEMISTRY 2010

NEW PATTERN
Friendsmania.net



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.
i. The significant figures in the number 5.734 are

• 2

• 3

• 4

• 5

ii. The Molecular Mass of Na2CO3 is

• 100 a.m.u

• 102 a.m.u

• 104 a.m.u

• 106 a.m.u

iii. The molecules which 64gm SO2 contains are

• 1.02 x 10(23)

• 2.04 x 10(23)

• 3.06 x 10(23)

• 6.02 x 10(23)

iv. The molecular formula of Vitamin "C" is C6H8O6. Its empirical formula is

• C2H3O2

• C3H4O3

• CH2O

• CHO2

v. At sea level and 0oC, the atmospheric pressure on each square inch of our body is

• 10.4 pounds

• 11.7 pounds

• 14.7 pounds

• 30 pounds

vi. The distance between the nuclei of two atoms forming a covalent bond is called

• Bond energy

• Atomic mass

• Bond length

• Ionic radius

vii. A double arrow in a chemical reaction indicates

• Reversible reaction

• incomplete reaction

• irreversible reaction

• Complete reaction

viii. Faraday's experiment indicates, the existence of

• Electron

• Proton

• X-rays

• Positron

ix. Which gas diffuses at the slowtest rate

• NH3

• CO

• N2

• SO2

x. CO2 has zero dipole moment because of its structure which is

• Linear

• Tetrahedron

• Angular

• Traingular

xi. Temperature volume relationship is called

• Boyle's Law

• Charle's Law

• Avagadro's Law

• Graham's Law

xii. Which of the following compounds have/has Sp3 hydridization.

• C2H2

• CH4

• CO2

• C2H2

xiii. The energy of activation of chemical reaction is 75.0 KJ mole-1 what will be its value in pressure of a positive catalyst?

• 53.3 KJ mole-1

• 76.9 KJ mole-1

• 87.6 KJ mole-1

• 109.1 KJ mole-1

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

• They are gas

• both contain carbon

• their molecular mass are same

• C3H8 is an organic compound

xv. The value of Kc is independent of

• Initial concentration of reactants

• Volume

• Catalyst

• Pressure

xvi. The reaction between an acid and an alcohol is called

• Neutralization

• Hydration

• Hydrolysis

• Dehydration

xvii. The solution which resists the changes in pH is called

• Saturated Solution

• Acidic Solution

• Molar Solution

• Buffer Solution

@import "/extensions/GoogleAdSense/GoogleAdSense.css";

SECTION "B" - SHORT ANSWER QUESTIONS

(40 MARKS)

Q.2. Answer any TEN questions from this section. All questions carry equal marks. The answer to each question should not exceed 6-8 lines.
1. Define the following terms

• Atomic Mass

• Molecular Formula

• Significant Figures

• Avagadro's Number

• Limiting Reactant

• Order of Reaction

• Intensive Properly

• Mole

2. Give the main posulates of the 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

• Avagadro's Law

3. Write two points of difference between each of the following

• Crystalline Solids & Amorphous Solids

• Isomorphisim & Polymorphism

• Emprical formula & Molecular Formula

4. Calculate the value of the gas constant R when "p" is expressed in atmospheres and "V" in dm3 and when MKS system is used.
OR
Derive the equation for the radius of the nth orbit of hydrogen atom using Bohr's Postulates.

5. Draw the shapes of s-orbital and p-orbital. Write down the names of the spectral lines of hydrogen atom.
OR
Write down the values of all the four quantum number for each of the two electrons of helium atom.

6. Diethyl Zinc is a chemical used in laboratory to protect the books from the worms. Its composition is 53% Zinc, 38.9% Carbon and 8.1% Hydrogen, find the emperical formula of the compound.
OR
Find the mass, number of moles and volume of Carbon Dioxide gas at S.T.P obtained on burning of 6.0g of carbon. Give also equation. Also find the number of molecules of CO2.
OR
You are provided with 6.0gm of C and 100 gm of O2. Calculate the amount of CO2 prepared by reacting them. Which of them is a limting reactant.
OR
Ethylene glycol is used in automobiles as antifreeze. It has 38.7% Carbon 9.7% Hydrogen and 51.6% Oxygen. Its molecular mass is 62.0 mol-1. Determine its molecular formula

7. Define Radioactivity. Describe the experiment to distinguish the three types of radioactive radiation.
OR
Write down five properties of each Alpha (α), Beta (β), Gamma (γ) rays.
OR
What are Cathode Rays? How are they produced? Discuss the five properties of Cathode Rays.

8. What do you understand by the ionic character of a covalent bond.
OR
Describe the ionic character of a covalent bond with one example.
OR
Define coordinate covalent bond and explain the formation of (NH+4).

9. Give a brief account of the following

• Viscosity

• Surface Tension

• Vapour Pressure

• Electron Affinity

• Electronegativity

• Buffer Solution

• Common Ion Effect

• Hydrolysis

• Hydration

• Neutralization

10. Write down the postulates of Arrhenius Theory of Ionization.
OR
Define the terms Oxidation and Reduction. Which of the substances is a reducing agent in the reaction Zn + H2SO4 ------> ZnSO4 + H2.

11. State the First Law of Thermodynamics. Derive the equation.

• ΔH = ΔE + PΔV

• Qp = ΔH

• ΔE = Qv

OR
State and explain Hass's Law of constant heat summation.

12. In a certain process 848J of heat is absorbed by s system, while 394J of work is done on the system. What is the change in internal energy of the process.
OR
Write down the electronic configuration for the ground state in Na (Z = 11) and Mg+2 (Z = 12).
OR
Give the number of protons, neutrons and electrons in 19/39K and 9/19F.

13. Arrange the following energy levels in ascending order using (n + 1) rule 4d, 3p, 7s, 4f, 2s.
OR
Calculate the wave number of radiation emitted in Lyman series of hydrogen atom when electron jumps from 2nd to Ist orbit.

14. For the reaction 2Hl(g) <-------> H2(g) + 12(g), one mole of Hl is introduced into a vessel at constant temperature, calculate the number of moles of I2 when the equilibrium reached (Kc = 0.0156).
OR
Will PbCrO4 precipitate from a solution prepared by mixing 200 cm3 of 2.5 x 10-4 M Pb(NO3)2 and 600 cm3 of 1.5 x 10-8 M K2Cro4? (Ksp of PbCrO4 = 1.8 x 10-14 mol-2 dm-6)

15. Give scientific reasons for the following

• A falling drop of a liquid is always spherical.

• Evaporation is a cooling process.

• Honey is more viscous than water.

• The bond angle is H2O is smaller than NH3.

• CO2 is a non polar molecule.

• Zinc dust when reacted with HCl produces hydrogen at a faster rate than a big piece of Zinc.

• Ionization potential of Oxygen is smaller than that of Nitrogen.

SECTION "C" - DETAILED ANSWER QUESTIONS

(28 MARKS)
NOTE Attempt any TWO questions from this Section. All questions carry equal marks:

Q.3 (A). Differentiate between the following

• Sigma bond and Pi bond

• sp3 - Hybridization and sp2 - Hydridization

• Atomic orbital and Molecular orbital

• Polar covalent bond and Non-polar covalent bond

• Valence bond Theory and Molecular ortibal Theory

• Intensive Properties and Extensive Properties

• Exothermic Reactions and Endothermic Reaction

Q.3 (B). Write down the points of Electron Pair Replusion Theory and Hybird Orbital Model. Describe the shapes and structures CH4, BeCl2, H2O, and NH3 on the basis of Electron Pair Replusion Theory.
OR
What is Dipole Moment? Explain the shapes of CO2 and H2O molecules with the help of dipole moment.
Q.3 (C). Describe the following rules of electronic configuration.

• Paulis Exclusion Principle

• Aufbau Principle

• (n + i) Rule

• Hand's Rule of Maximum Multiplicity

OR
Differentiate between the following

• Principal Quantum Number and Azimathal Quantum Number

• Line Spectrum and Continuous Spectrum

• Orbit and Orbital

• Natural Radioactivity and Artificial Radioactivity.

Q.4 (A). State the Law of Mass Action. Derive the equilibrium constant Kc for the reaction nA + nB <--------> xC + yD.
OR
State Rutheford's Nuclear Model of an atom on the basis of Rutherford's Experiment.
OR
What are the defects of Rutherford's Atomic Model? How Neil Bohr corrected them. Describe the postulates of Bohr's Atomic Theory.
OR
State and explain Le-Chatelier's Principle.
Q.4 (B). What are ionization Potential and Electron Affinity. Discuss the formation of bond between Sodium and Chlorine.
OR
Define Solubility Product and give its example and application.
OR
What is Electrode Potential? How is electrode potential and Zinc and Copper discovered.
OR
Define rate of reaction describe methods to determine the rate of reaction and also describe the factors which affect the rate of reaction.
Q.4 (C). Calculate the rate constant for the reaction A + B --------> AB when the initial concentration of each of the reactant is 0.01 mol-1 dm-3 S-1.
OR
The volume of a given mass of a gas at 127°C is 2.0 dm3. What will be its volume at 254°C when pressure remains constant.
@import "/extensions/GoogleAdSense/GoogleAdSense.css";

Q.5 (A). Differentiate between the following

• Activation Energy and Threshold Energy

• Positive Catalyst & Negative Catalyst

• Rate of Reaction & Rate Constant

OR
Define the following terms

• Enlthalpy

• System

• Heat of Formation

• Thermodynamics

• Surroundings

• State

• Thershold Energy

• Activation Energy

• Inhibitor

• Indicator

Q.5 (B) i. Find the Oxidation number of Sulphur in H2SO4, SO2, H2S, SO3(-2)
Q.5 (B) ii. Balance the following equation by Ion Electron method.
Fe(+3) + MnO4(-1) ----------> Fe+3 + Mn(+2) + H2O
Q.3 (C). Name the crystal system which has the following axis and angle.

• a = b = c; α = β = γ = 90°

• a = b ≠ c; α = β = γ = 90°

• a ≠ b ≠ c; α = β = γ = 90°

• a = b ≠ c; α = β = γ = 90°