In a galvanic cell, oxidation occurs at the anode.
Correct Answer: B — Oxidation occurs
Q. In a reaction at equilibrium, if the concentration of a reactant is decreased, what will happen?
A.Shift to the right
B.Shift to the left
C.No change
D.Increase the rate of reaction
Solution
According to Le Chatelier's principle, decreasing the concentration of a reactant will shift the equilibrium to the left to produce more reactants.
Correct Answer: B — Shift to the left
Q. In a reaction at equilibrium, if the concentration of products is decreased, what will happen?
A.Shift to the right
B.Shift to the left
C.No change
D.Depends on the temperature
Solution
Decreasing the concentration of products will shift the equilibrium to the right to produce more products, according to Le Chatelier's principle.
Correct Answer: A — Shift to the right
Q. In a reaction at equilibrium, if the concentration of reactants is increased, what will happen to the equilibrium position?
A.Shift to the right
B.Shift to the left
C.No change
D.Depends on the reaction
Solution
According to Le Chatelier's principle, increasing the concentration of reactants will shift the equilibrium position to the right to produce more products.
Correct Answer: A — Shift to the right
Q. In a reaction at equilibrium, if the temperature is decreased, what will happen to the equilibrium position if the reaction is exothermic?
A.Shift to the right
B.Shift to the left
C.No change
D.Depends on the concentration
Solution
For an exothermic reaction, decreasing the temperature shifts the equilibrium to the right, favoring the formation of products.
Correct Answer: A — Shift to the right
Q. In a reaction at equilibrium, if the temperature is increased and the reaction is exothermic, what will happen to the equilibrium position?
A.Shift to the right
B.Shift to the left
C.No change
D.Equilibrium constant increases
Solution
For an exothermic reaction, increasing the temperature shifts the equilibrium position to the left, favoring the reactants.
Correct Answer: B — Shift to the left
Q. In a reaction mechanism, the slowest step is known as the:
A.Rate-determining step
B.Intermediate step
C.Fast step
D.Catalytic step
Solution
The slowest step in a reaction mechanism is called the rate-determining step, as it controls the overall reaction rate.
Correct Answer: A — Rate-determining step
Q. In a reaction mechanism, the slowest step is known as what?
A.Rate-determining step
B.Intermediate step
C.Fast step
D.Catalytic step
Solution
The slowest step in a reaction mechanism is known as the rate-determining step.
Correct Answer: A — Rate-determining step
Q. In a reaction where 2 moles of hydrogen react with 1 mole of oxygen, how many moles of water are produced?
A.1 mole
B.2 moles
C.3 moles
D.4 moles
Solution
According to the balanced equation 2H2 + O2 → 2H2O, 2 moles of H2 produce 2 moles of H2O.
Correct Answer: B — 2 moles
Q. In a reaction, 3 moles of A react with 2 moles of B to produce 4 moles of C. What is the mole ratio of A to C?
A.3:4
B.2:3
C.4:3
D.1:1
Solution
The mole ratio of A to C is 3:4 based on the coefficients in the balanced equation.
Correct Answer: A — 3:4
Q. In a redox reaction, which species is reduced?
A.Oxidizing agent
B.Reducing agent
C.Product
D.Reactant
Solution
The oxidizing agent is the species that gains electrons and is reduced.
Correct Answer: A — Oxidizing agent
Q. In a reversible process, the change in Gibbs free energy (ΔG) is:
A.Always positive
B.Always negative
C.Zero at equilibrium
D.None of the above
Solution
In a reversible process, the change in Gibbs free energy (ΔG) is zero at equilibrium.
Correct Answer: C — Zero at equilibrium
Q. In a solution of a non-volatile solute, how does the vapor pressure compare to that of the pure solvent?
A.Higher than the pure solvent
B.Lower than the pure solvent
C.Equal to the pure solvent
D.Depends on the temperature
Solution
The presence of a non-volatile solute lowers the vapor pressure of the solvent compared to that of the pure solvent.
Correct Answer: B — Lower than the pure solvent
Q. In a solution of volatile components A and B, if the vapor pressure of A is 80 mmHg and that of B is 20 mmHg, what is the total vapor pressure?
A.100 mmHg
B.80 mmHg
C.60 mmHg
D.20 mmHg
Solution
The total vapor pressure of a solution is the sum of the partial vapor pressures of its components: 80 mmHg + 20 mmHg = 100 mmHg.
Correct Answer: A — 100 mmHg
Q. In a spontaneous process, the change in Gibbs free energy (ΔG) is:
A.Positive
B.Negative
C.Zero
D.Undefined
Solution
For a spontaneous process, the change in Gibbs free energy (ΔG) is negative.
Correct Answer: B — Negative
Q. In a zero-order reaction, the rate of reaction is independent of which of the following?
A.Concentration of reactants
B.Temperature
C.Catalyst
D.All of the above
Solution
In a zero-order reaction, the rate of reaction is independent of the concentration of reactants.
Correct Answer: A — Concentration of reactants
Q. In an endothermic reaction, the enthalpy of the products is ____ than that of the reactants.
A.higher
B.lower
C.equal
D.unpredictable
Solution
In an endothermic reaction, the enthalpy of the products is higher than that of the reactants.
Correct Answer: A — higher
Q. In an ideal solution, the enthalpy of mixing is:
A.Positive
B.Negative
C.Zero
D.Varies with concentration
Solution
In an ideal solution, the enthalpy of mixing is zero, indicating no heat is absorbed or released during mixing.
Correct Answer: C — Zero
Q. In the equilibrium constant expression Kc, what is the unit for Kc if the reaction is A(g) + B(g) ⇌ C(g)?
A.mol/L
B.L/mol
C.dimensionless
D.mol^2/L^2
Solution
The equilibrium constant Kc is dimensionless because it is a ratio of concentrations raised to their stoichiometric coefficients.
Correct Answer: C — dimensionless
Q. In the ideal gas equation PV=nRT, what does 'n' represent?
A.Pressure
B.Volume
C.Number of moles
D.Temperature
Solution
'n' represents the number of moles of the gas in the ideal gas equation.
Correct Answer: C — Number of moles
Q. In the Langmuir adsorption isotherm, what does the term 'b' represent?
A.Adsorption energy
B.Surface area
C.Equilibrium constant
D.Adsorption capacity
Solution
'b' in the Langmuir isotherm represents the equilibrium constant related to the adsorption process.
Correct Answer: C — Equilibrium constant
Q. In the molecular orbital diagram of diatomic nitrogen (N2), which orbitals are filled first?
A.σ2s, σ*2s
B.σ2p, π2p
C.π2p, σ2p
D.σ*2p, π*2p
Solution
In N2, the 2s orbitals (σ2s and σ*2s) are filled before the 2p orbitals.
Correct Answer: A — σ2s, σ*2s
Q. In the molecular orbital theory, which of the following is true for the π molecular orbitals?
A.They are formed by end-to-end overlap.
B.They are lower in energy than σ orbitals.
C.They can accommodate a maximum of 2 electrons.
D.They are always bonding.
Solution
π molecular orbitals can accommodate a maximum of 2 electrons, similar to all molecular orbitals.
Correct Answer: C — They can accommodate a maximum of 2 electrons.
Q. In the molecular orbital theory, which of the following orbitals is lower in energy for homonuclear diatomic molecules?
A.σ2p
B.π2p
C.σ2s
D.π2s
Solution
The σ2s orbital is lower in energy than the π2p and σ2p orbitals in homonuclear diatomic molecules.
Correct Answer: C — σ2s
Q. In the molecular orbital theory, which of the following orbitals is lower in energy than the 2p orbitals?
A.2s
B.3s
C.2p
D.3p
Solution
The 2s molecular orbitals are lower in energy than the 2p molecular orbitals.
Correct Answer: A — 2s
Q. In the molecular orbital theory, which of the following orbitals is the highest energy in O2?
A.σ2p
B.π2p
C.σ*2p
D.π*2p
Solution
The highest energy orbital in O2 is σ*2p, which is an antibonding orbital.
Correct Answer: C — σ*2p
Q. In the molecular orbital theory, which of the following orbitals is the highest occupied molecular orbital (HOMO) in O2?
A.σ2p
B.π2p
C.σ*2p
D.π*2p
Solution
In O2, the highest occupied molecular orbital (HOMO) is π2p.
Correct Answer: B — π2p
Q. In the molecular orbital theory, which of the following pairs of orbitals can combine to form a sigma bond?
A.s and p
B.p and p
C.s and s
D.d and p
Solution
s and s orbitals can combine to form a sigma bond.
Correct Answer: C — s and s
Q. In the reaction 2AgNO3 + Cu → 2Ag + Cu(NO3)2, what is the oxidation state of silver in AgNO3?
A.+1
B.0
C.+2
D.+3
Solution
In AgNO3, silver has an oxidation state of +1.
Correct Answer: A — +1
Q. In the reaction 2Ag^+ + Zn → 2Ag + Zn^2+, what is the oxidation state change for zinc?
A.0 to +2
B.+2 to 0
C.+2 to +1
D.0 to -1
Solution
Zinc is oxidized from an oxidation state of 0 to +2.
