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FPSC · CSS 2023

Chemistry, Paper I

100 marks · 3 hours · 7 questions · official PDF, 1 page
This paper Chemistry · all yearsQ. 2 · The following reaction occurs via…Q. 3 · An explosion is usually considered…Q. 4 · Describe Schrodinger Wave Equation for…Q. 5 · Describe Nernst's equation.Q. 6 · Describe three methods of mechanical…Q. 7 · (a) Compare Valence Bond Theory…Q. 8 · Discuss the following in detail.With this paperOfficial PDF1 pp← 20222023 →
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Part II

Q. 2
  1. (a)The following reaction occurs via two steps, where the first step is rate-determining step. Step I NO 2 (g) + NO 2 (g) → NO(g) + NO 3 (g) Step II NO 3 (g) + CO(g) → NO 2 (g) + CO 2 (g) Write down the rate equation for the above reaction. Which molecule acts as a catalyst in this reaction? Give a reason. Which molecule is an intermediate in this reaction and justify it. [12]
  2. (b)Describe Arrhenius's equation. [8]
(20)
Q. 3
  1. (a)An explosion is usually considered adiabatic, indicating negligible heat transfer, even though it's rapidly expanding gaseous products are not at the same temperature as the surroundings, and the boundary permits heat transfer. Explain the phenomenon. [10]
  2. (b)Draw a working diagram for a reversible heat engine that operates with two isothermal steps and two constant-pressure steps. How many heat reservoirs are needed to operate this engine? [10]
(20)
Q. 4
  1. (a)Describe Schrodinger Wave Equation for a particle in a three-dimensional box. [10]
  2. (b)Explain photoelectric effect. [8]
  3. (c)What is a wave function? Give Born's interpretation of wave function. [2]
(20)
Q. 5
  1. (a)Describe Nernst's equation. [10]
  2. (b)Describe the significance of pH, pK a , and pK b . [6]
  3. (c)What is the relationship between conductance and Kohlrausch's law? [4]
(20)
Q. 6
  1. (a)Describe three methods of mechanical phase separation. [10]
  2. (b)Briefly discuss "The Hard-Soft Acid-Base Principle." [10]
(20)
Q. 7

(a) Compare Valence Bond Theory with Molecular Orbital Theory.

(b) What is the oxidation state? Differentiate between the oxidation state and valency /covalency of an element with suitable examples.

(c) Write the molecular orbital configuration of the followings:

O2+\mathrm{O_2^+} , O2\mathrm{O_2} , O2−\mathrm{O_2^-} and O2−2\mathrm{O_2^{-2}}

Checked against official paper
(20)
Q. 8

Discuss the following in detail.

  1. (i)Crystal Field Theory [5]
  2. (ii)Hess's Law [5]
  3. (iii)Electrophoresis Technique [5]
  4. (iv)Freundlich Adsorption Isotherm [5]
(20)

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About this paper

The 2023 CSS Chemistry paper set by the Federal Public Service Commission. Question wording only; questions marked “Not yet checked” have not been compared with the official paper yet. Open the official paper beside the questions to check any of them.

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