Physical Chemistry
Q. What is the relationship between the equilibrium constant (K) and the Gibbs free energy change (ΔG) for a reaction?
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A.
ΔG = -RT ln(K)
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B.
ΔG = RT ln(K)
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C.
ΔG = KRT
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D.
ΔG = K/R
Solution
The relationship is given by the equation ΔG = -RT ln(K), where R is the gas constant and T is the temperature in Kelvin.
Correct Answer: A — ΔG = -RT ln(K)
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Q. What is the relationship between the equilibrium constants Kp and Kc for a gaseous reaction?
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A.
Kp = Kc
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B.
Kp = Kc(RT)^(Δn)
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C.
Kp = Kc/RT
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D.
Kp = Kc(RT)^(Δn) where Δn is the change in moles of gas
Solution
The relationship between Kp and Kc is given by Kp = Kc(RT)^(Δn), where Δn is the change in the number of moles of gas.
Correct Answer: B — Kp = Kc(RT)^(Δn)
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Q. What is the relationship between the Gibbs free energy change (ΔG) and the equilibrium constant (K)?
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A.
ΔG = -RT ln(K)
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B.
ΔG = RT ln(K)
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C.
ΔG = K - RT
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D.
ΔG = 0 at equilibrium
Solution
The relationship is given by the equation ΔG = -RT ln(K), where R is the gas constant and T is the temperature in Kelvin.
Correct Answer: A — ΔG = -RT ln(K)
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Q. What is the relationship between the molality of a solution and its boiling point elevation?
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A.
Directly proportional
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B.
Inversely proportional
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C.
No relationship
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D.
Exponential relationship
Solution
Boiling point elevation is directly proportional to the molality of the solution.
Correct Answer: A — Directly proportional
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Q. What is the relationship between ΔG and equilibrium constant K?
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A.
ΔG = -RT ln K
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B.
ΔG = RT ln K
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C.
ΔG = KRT
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D.
ΔG = K/R
Solution
The relationship is given by ΔG = -RT ln K, where R is the gas constant and T is temperature.
Correct Answer: A — ΔG = -RT ln K
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Q. What is the relationship between ΔG and the equilibrium constant (K)?
-
A.
ΔG = -RT ln(K)
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B.
ΔG = RT ln(K)
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C.
ΔG = KRT
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D.
ΔG = K - RT
Solution
The relationship is given by ΔG = -RT ln(K), where R is the gas constant and T is the temperature in Kelvin.
Correct Answer: A — ΔG = -RT ln(K)
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Q. What is the relationship between ΔG, ΔH, and ΔS at constant temperature?
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A.
ΔG = ΔH + TΔS
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B.
ΔG = ΔH - TΔS
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C.
ΔG = TΔS - ΔH
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D.
ΔG = ΔH/ΔS
Solution
The relationship is given by the equation ΔG = ΔH - TΔS, where T is the temperature in Kelvin.
Correct Answer: B — ΔG = ΔH - TΔS
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Q. What is the relationship between ΔH and ΔG at equilibrium?
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A.
ΔG = 0
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B.
ΔH = 0
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C.
ΔG = ΔH
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D.
ΔG = ΔH + TΔS
Solution
At equilibrium, the change in Gibbs free energy (ΔG) is zero.
Correct Answer: A — ΔG = 0
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Q. What is the relationship between ΔH and ΔU for a reaction at constant pressure?
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A.
ΔH = ΔU + PΔV
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B.
ΔH = ΔU - PΔV
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C.
ΔH = ΔU
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D.
ΔH = PΔV
Solution
At constant pressure, the relationship is given by ΔH = ΔU + PΔV.
Correct Answer: A — ΔH = ΔU + PΔV
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Q. What is the role of a catalyst in a redox reaction?
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A.
Increase oxidation
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B.
Increase reduction
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C.
Speed up the reaction
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D.
Change the products
Solution
A catalyst speeds up the reaction without being consumed in the process.
Correct Answer: C — Speed up the reaction
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Q. What is the role of a salt bridge in a galvanic cell?
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A.
To provide a pathway for electrons
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B.
To maintain charge balance
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C.
To increase voltage
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D.
To decrease resistance
Solution
The salt bridge maintains charge balance by allowing ions to flow between the two half-cells.
Correct Answer: B — To maintain charge balance
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Q. What is the role of activated charcoal in adsorption processes?
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A.
Catalyst
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B.
Adsorbent
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C.
Solvent
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D.
Reagent
Solution
Activated charcoal is commonly used as an adsorbent due to its high surface area and porosity.
Correct Answer: B — Adsorbent
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Q. What is the role of the cathode in an electrochemical cell?
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A.
Oxidation occurs
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B.
Reduction occurs
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C.
Electrons are lost
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D.
Ions are produced
Solution
In an electrochemical cell, reduction occurs at the cathode.
Correct Answer: B — Reduction occurs
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Q. What is the shape of a molecule with the formula AX3E?
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A.
Trigonal planar
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B.
Tetrahedral
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C.
Trigonal pyramidal
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D.
Bent
Solution
AX3E indicates three bonding pairs and one lone pair, resulting in a trigonal pyramidal shape.
Correct Answer: C — Trigonal pyramidal
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Q. What is the shape of the ammonia (NH3) molecule?
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A.
Linear
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B.
Trigonal planar
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C.
Tetrahedral
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D.
Trigonal pyramidal
Solution
Ammonia has a trigonal pyramidal shape due to the presence of a lone pair on the nitrogen atom.
Correct Answer: D — Trigonal pyramidal
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Q. What is the shape of the d orbitals?
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A.
Spherical
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B.
Dumbbell
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C.
Double dumbbell
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D.
Linear
Solution
The d orbitals have a double dumbbell shape.
Correct Answer: C — Double dumbbell
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Q. What is the shape of the molecular orbital in the case of a π bond?
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A.
Spherical
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B.
Dumbbell
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C.
Linear
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D.
Planar
Solution
π bonds are formed by the side-to-side overlap of p orbitals, resulting in a planar shape.
Correct Answer: D — Planar
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Q. What is the shape of the molecular orbital in the highest occupied molecular orbital (HOMO) of benzene?
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A.
Linear
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B.
Trigonal planar
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C.
Tetrahedral
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D.
Cyclic
Solution
The HOMO of benzene is cyclic due to the delocalization of π electrons in the ring structure.
Correct Answer: D — Cyclic
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Q. What is the shape of the molecular orbital of the highest energy in O2?
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A.
spherical
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B.
dumbbell
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C.
double dumbbell
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D.
linear
Solution
The highest energy molecular orbital in O2 is a π* orbital, which has a dumbbell shape.
Correct Answer: B — dumbbell
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Q. What is the shape of the molecular orbital of the highest energy in the O2 molecule?
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A.
Linear
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B.
Bent
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C.
Planar
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D.
Diatomic
Solution
The highest energy molecular orbital in O2 is a diatomic molecular orbital, specifically a π* orbital.
Correct Answer: D — Diatomic
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Q. What is the shape of the molecule PCl5?
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A.
Trigonal bipyramidal
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B.
Octahedral
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C.
Tetrahedral
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D.
Square planar
Solution
PCl5 has a trigonal bipyramidal shape due to five bonding pairs around the phosphorus atom.
Correct Answer: A — Trigonal bipyramidal
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Q. What is the shape of the molecule SF6 according to VSEPR theory?
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A.
Square planar
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B.
Octahedral
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C.
Trigonal bipyramidal
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D.
Tetrahedral
Solution
SF6 has six bonding pairs and no lone pairs, leading to an octahedral shape.
Correct Answer: B — Octahedral
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Q. What is the shape of the molecule with the formula AX2E2 according to VSEPR theory?
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A.
Linear
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B.
Bent
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C.
Trigonal planar
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D.
Tetrahedral
Solution
AX2E2 indicates two bonding pairs and two lone pairs, resulting in a bent shape.
Correct Answer: B — Bent
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Q. What is the shape of the molecule with the formula AX3E?
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A.
Tetrahedral
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B.
Trigonal pyramidal
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C.
Trigonal planar
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D.
Bent
Solution
AX3E indicates three bonding pairs and one lone pair, resulting in a trigonal pyramidal shape.
Correct Answer: B — Trigonal pyramidal
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Q. What is the shape of the molecule with the formula AX4?
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A.
Tetrahedral
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B.
Square planar
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C.
Trigonal bipyramidal
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D.
Octahedral
Solution
AX4 indicates four bonding pairs and no lone pairs, resulting in a tetrahedral shape.
Correct Answer: A — Tetrahedral
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Q. What is the shape of the p-orbital?
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A.
Spherical
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B.
Dumbbell
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C.
Double dumbbell
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D.
Linear
Solution
The p-orbital has a dumbbell shape.
Correct Answer: B — Dumbbell
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Q. What is the shape of the water molecule (H2O)?
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A.
Linear
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B.
Bent
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C.
Trigonal planar
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D.
Tetrahedral
Solution
The water molecule has a bent shape due to the two lone pairs on the oxygen atom.
Correct Answer: B — Bent
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Q. What is the significance of the BET theory in surface chemistry?
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A.
Describes physisorption
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B.
Describes chemisorption
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C.
Determines surface area of solids
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D.
Calculates adsorption energy
Solution
The BET theory is significant for determining the surface area of solids based on multilayer adsorption.
Correct Answer: C — Determines surface area of solids
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Q. What is the significance of the Gibbs Free Energy in chemical thermodynamics?
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A.
It predicts the direction of a reaction.
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B.
It measures the heat of reaction.
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C.
It indicates the concentration of reactants.
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D.
It determines the rate of reaction.
Solution
Gibbs Free Energy is crucial for predicting the spontaneity and direction of a chemical reaction.
Correct Answer: A — It predicts the direction of a reaction.
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Q. What is the significance of the Gibbs Free Energy of formation (ΔGf°)?
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A.
It indicates the stability of a compound.
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B.
It is the energy required to form a compound from its elements.
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C.
It is always negative.
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D.
It is temperature dependent.
Solution
ΔGf° indicates the energy change when a compound is formed from its elements in their standard states.
Correct Answer: B — It is the energy required to form a compound from its elements.
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