Q. The half-life of a first-order reaction is independent of the initial concentration of the reactant. What is the expression for the half-life (t1/2)? (2022)
A.t1/2 = 0.693/k
B.t1/2 = k/0.693
C.t1/2 = 1/k
D.t1/2 = k/2
Solution
The half-life of a first-order reaction is given by the expression t1/2 = 0.693/k, where k is the rate constant.
Q. The half-life of a first-order reaction is independent of the initial concentration of the reactant. What is the expression for the half-life? (2022)
A.t₁/₂ = 0.693/k
B.t₁/₂ = k/0.693
C.t₁/₂ = 1/k
D.t₁/₂ = k/1
Solution
The half-life of a first-order reaction is given by t₁/₂ = 0.693/k.
Q. The half-life of a first-order reaction is independent of the initial concentration of the reactant. What is the expression for the half-life (t₁/₂)? (2022)
A.t₁/₂ = 0.693/k
B.t₁/₂ = k/0.693
C.t₁/₂ = 1/k
D.t₁/₂ = k/1
Solution
The half-life of a first-order reaction is given by t₁/₂ = 0.693/k.
Q. The heat capacity of a substance is defined as: (2023)
A.The amount of heat required to raise the temperature of one gram by one degree Celsius.
B.The amount of heat required to raise the temperature of one mole by one degree Celsius.
C.The total heat content of the substance.
D.The heat required to change the state of the substance.
Solution
The heat capacity of a substance is defined as the amount of heat required to raise the temperature of one mole of the substance by one degree Celsius.
Correct Answer: B — The amount of heat required to raise the temperature of one mole by one degree Celsius.
Q. The rate of a reaction is defined as the change in concentration of a reactant or product per unit time. What is the general form of the rate equation? (2023)
A.Rate = k[A]^n
B.Rate = k[A][B]
C.Rate = k[A]^2[B]
D.Rate = k[A] + [B]
Solution
The general form of the rate equation is Rate = k[A]^n, where n is the order of the reaction.
Q. The rate of a reaction is directly proportional to the concentration of one reactant raised to the power of 2. What is the order of the reaction? (2022)
A.Zero order
B.First order
C.Second order
D.Third order
Solution
If the rate is proportional to the concentration of one reactant raised to the power of 2, the reaction is second order.
Q. The rate of a reaction is directly proportional to the product of the concentrations of the reactants raised to their respective powers. This statement defines:
A.Rate law
B.Equilibrium constant
C.Reaction quotient
D.Catalytic efficiency
Solution
This statement defines the rate law of a reaction.
Q. The rate of a reaction is directly proportional to the product of the concentrations of the reactants raised to their respective powers. This statement defines which law?
A.Law of conservation of mass
B.Rate law
C.Le Chatelier's principle
D.Gibbs free energy
Solution
This statement defines the rate law of a chemical reaction.
Q. What is the boiling point elevation for a solution with 0.5 moles of a non-volatile solute in 1 kg of water? (Kb for water = 0.512 °C kg/mol) (2022)
A.0.256 °C
B.0.512 °C
C.1.024 °C
D.0.128 °C
Solution
Boiling point elevation (ΔTb) = Kb * m = 0.512 °C kg/mol * 0.5 mol/kg = 0.256 °C.