Chemistry Exam

21. Consider the following equilibrium reaction at 298 K:
2NO₂(g) ↔ 2NO(g) + O₂(g)
P_NO₂ = 0.75 atm P_NO = 2.5 x 10⁻⁵ P_O₂ = 3.5 x 10⁻⁵ atm
What is the equilibrium constant (K_p) at this temperature?

A. 1.16 x 10⁻⁹
B. 5.2 x 10⁻¹⁵
C. 3.9 x 10⁻¹⁴
D. 2.9 x 10⁻¹⁴

22. The molecule of BrF₅ has both bonding and lone pair of electrons. Based upon these electrons, which one the CORRECT molecular geometry of the molecule of BrF₅?

A. Square pyramidal
B. Square planar

C. Trigonal bipyramidal
D. Trigonal pyramidal

23. Consider the structure of an alcohol shown below:

CH₃CHCH₂CH₂CHCH₃
   |       |
  OH       OH

What type of an alcohol is it?

A. Polyhydric alcohol
B. Tertiary alcohol
C. Dihydric alcohol
D. Primary alcohol

24. What is the IUPAC name of the following carboxylic acid?

  O    Cl            O
  ||   |             ||
HOC CH₂CHCH₂CH₂CH₂CH₂COH

A. 3-chlorooctanedioic acid
B. 5-chlorooctanoic acid
C. 3-chlorooctanoic acid
D. 2-chlorooctanedioic acid

25. Which statement below CORRECTLY distinguishes redox and non-redox reactions?

A. Reduction occurs in redox reactions and oxidation takes place in non-redox reactions.
B. Electrons are transferred in redox reactions but not in non-redox reactions.
C. Acid-base reactions can be considered as both redox and non-redox reactions.
D. Oxidation number remains the same in both redox and non-redox reactions.

26. Given the reaction C(s) + CO₂(g) ↔ 2CO(g) What is the equilibrium constant expression for the reaction?

A. [CO]² / [CO₂]
B. [CO]² / [C][CO₂]
C. [C][CO₂] / [CO]²
D. [CO₂] / [C]

27. Which of the following pair of substances can be considered as examples of the liquid state of matter at room temperature and 1 atm pressure?

A. Water and carbon dioxide
B. Carbon and mercury
C. Carbon and carbon monoxide
D. Water and mercury

28. Which gas law describes the behavior of gases using the variables: temperature, volume, pressure and number of moles?

A. Boyle's law
B. Ideal gas law
C. Combined gas law
D. Avogadro's law

29. Which one of the following CORRECTLY illustrates the hybridization of orbitals of Be in the molecule BeCl₂?

A. [Diagram A]
B. [Diagram B]
C. [Diagram C]
D. [Diagram D]

30. What is the electron configuration of O₂ molecule as per the molecular orbital model? (Atomic number of O = 8)

A. σ₁s², σ*₁s², σ₂s², σ*₂s², σ₂pₓ², (π₂pᵧ² = π₂p₂²) (π₂pᵧ²* = π₂p₂²*)
B. σ₁s², σ*₁s², σ₂s², σ*₂s², σ₂pₓ², (π₂pᵧ² = π₂p₂²) (π₂pᵧ²* = π₂p₂¹*)
C. σ₁s², σ*₁s², σ₂s², σ*₂s², σ₂pₓ², (π₂pᵧ² = π₂p₂²) (π₂pᵧ¹* = π₂p₂¹*)
D. σ₁s², σ*₁s², σ₂s², σ*₂s², σ₂pₓ², (π₂pᵧ² = π₂p₂²) (π₂p₂²*)

31. Which of the following factors does NOT affect the rate of a chemical reaction having solid reactants?

A. Temperature of reaction
B. Concentration of reactants
C. Volume of reaction vessel
D. Physical state of reactants

32. At a particular temperature, the equilibrium constant, K_c = 0.36 for the reaction
SO₃(g) ↔ SO₂(g) + O₂(g)
In an experiment, 1.00 mol of SO₃ is introduced into a 1.00 L container. It was found that there is 0.50 mol of SO₂ at equilibrium in the same volume. Which of the following predictions can be drawn from the given data?

A. The reaction will proceed to the left.
B. The reaction is at equilibrium.
C. It is not possible to predict the direction of the reaction.
D. The reaction will proceed to the right.

33. What is the bond formed between two or more atoms by sharing of electrons?

A. Metallic bond
B. Ionic bond
C. Valence bond
D. Covalent bond

34. Which statement below CORRECTLY describes dipole-dipole forces? It is the force that exists

A. between polar molecules.
B. in all molecules.
C. between polar and non-polar molecules.
D. between non-polar molecules.

35. Comparing the forces between molecules of similar molar masses, which one of the following produces the weakest force?

A. Hydrogen bonding
B. Covalent bonds
C. Van der-Waals's forces.
D. Ionic forces.

36. What is a limiting reactant? It is the reactant that

A. remains unreacted as the reaction proceeds.
B. regenerated at the end of the reaction.
C. completely consumed when the reaction goes to completion.
D. present in excess when the reaction goes to completion.

37. What is the density of methane (CH₄) at a pressure of 900 torr and a temperature of 25°C? (R = 0.082 atm L/mol·K, 1 atm = 760 torr)

A. 0.92
B. 0.78
C. 9.2
D. 1.25

38. It takes 2.25 minutes for 0.02 mol of He to diffuse. How long will it take to diffuse for the same amount of methane gas, CH₄? (M.wt of He = 4 g/mol, CH₄=16 g/mol)

A. 2.25 min
B. 1.25 min
C. 6 min
D. 4.5 min

39. Which one of the following statement CORRECTLY defines rate of reaction? The rate of a reaction is

A. the measure of the amount of energy change in a chemical reaction.
B. the changes in concentration of reactants or products per unit time.
C. the measure of the rate of diffusion of different gases inside a tube.
D. the study of necessary mechanisms occurred in a chemical reaction.

40. Consider the following gaseous reversible reaction is at a state of equilibrium:
PCl₃(g) + Cl₂(g) ↔ PCl₅(g)
Which of the following changes in concentration will cause the equilibrium shift to the right?

A. Increasing the concentration of the reactants and products equivalently.
B. Decreasing the concentrations of the reactants and products equivalently.
C. Decreasing the concentrations of the reactants and increasing the concentration of the product.
D. Increasing the concentrations of the reactants and decreasing the concentration of the product.

Chemistry Exam: Part 2

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