Q. In a reversible reaction at equilibrium, what happens if the temperature is increased? (2019)
A.The reaction shifts to the exothermic side
B.The reaction shifts to the endothermic side
C.No change occurs
D.The reaction rate decreases
Solution
Increasing the temperature of an exothermic reaction shifts the equilibrium to the left (towards the reactants), while for an endothermic reaction, it shifts to the right (towards the products).
Correct Answer: B — The reaction shifts to the endothermic side
Q. In a reversible reaction at equilibrium, which of the following statements is true?
A.The rate of the forward reaction is equal to the rate of the reverse reaction.
B.The concentration of reactants is greater than products.
C.The reaction has stopped completely.
D.The temperature remains constant.
Solution
At equilibrium, the rate of the forward reaction equals the rate of the reverse reaction, which means the concentrations of reactants and products remain constant over time.
Correct Answer: A — The rate of the forward reaction is equal to the rate of the reverse reaction.
Q. In a reversible reaction, if the concentration of products increases, what happens to the rate of the forward reaction? (2021)
A.It increases
B.It decreases
C.It remains constant
D.It becomes zero
Solution
According to Le Chatelier's principle, if the concentration of products increases, the system will shift to the left, decreasing the rate of the forward reaction.
Q. In a reversible reaction, if the concentration of products is increased, what will happen to the equilibrium position? (2021)
A.Shift to the left
B.Shift to the right
C.No change
D.Depends on temperature
Solution
According to Le Chatelier's principle, increasing the concentration of products will shift the equilibrium position to the left to counteract the change.
Q. In a reversible reaction, if the concentration of reactants is increased, what will happen to the equilibrium position? (2021)
A.It will shift to the right
B.It will shift to the left
C.It will remain unchanged
D.It will shift to the center
Solution
According to Le Chatelier's principle, if the concentration of reactants is increased, the equilibrium will shift to the right to favor the formation of products.
Q. In a reversible reaction, if the concentration of reactants is increased, what will happen to the position of equilibrium? (2021)
A.It will shift to the right
B.It will shift to the left
C.It will remain unchanged
D.It will shift to the center
Solution
According to Le Chatelier's principle, increasing the concentration of reactants will shift the equilibrium position to the right to favor the formation of products.
Q. In a reversible reaction, if the concentration of the reactants is increased, what will happen to the position of equilibrium? (2023)
A.It will shift to the right
B.It will shift to the left
C.It will remain unchanged
D.It will shift to the center
Solution
According to Le Chatelier's principle, increasing the concentration of reactants will shift the equilibrium position to the right, favoring the formation of products.
Q. In a second-order reaction, if the initial concentration is 0.1 M and the rate constant is 0.05 M⁻¹s⁻¹, what is the time taken to reach half the initial concentration? (2020)
A.10 s
B.20 s
C.5 s
D.15 s
Solution
For a second-order reaction, t₁/₂ = 1 / (k[A₀]) = 1 / (0.05 * 0.1) = 200 s.
Q. In a series RLC circuit, at resonance, the impedance is equal to which of the following? (2020)
A.Zero
B.R
C.XL
D.XC
Solution
At resonance in a series RLC circuit, the impedance (Z) is equal to the resistance (R) because the inductive and capacitive reactances cancel each other out.
Q. In a series RLC circuit, if the total impedance is 50Ω, the resistance is 30Ω, what is the inductive reactance if the capacitive reactance is 20Ω? (2023)
A.10Ω
B.20Ω
C.30Ω
D.40Ω
Solution
Using Z = √(R² + (XL - XC)²), we find XL = √(50² - 30²) + 20 = 10Ω.
