JEE Main · 2005 · 08 May 2005 · Offline · Chemical Kinetics

Consider an endothermic reaction,

X ⟶ Y

with the activation energies

E_{b}

and

E_{f}

for the backward and forward reactions, respectively. In general

(A) $E_{b} < E_{f}$ ✓ Correct
(B) $E_{b} > E_{f}$
(C) $E_{b} = E_{f}$
(D)There is no definite relation between $E_{b}$ and $E_{f}$

Answer: (A)

Solution

Picture the energy profile: the forward and backward activation barriers are measured from the reactant and product valleys up to the same transition-state peak, and their difference is the reaction enthalpy,

Δ H = E_{f} - E_{b}

. An endothermic reaction has

Δ H > 0

, which means

E_{f} - E_{b} > 0

, so the forward barrier is the taller one and

E_{b} < E_{f}

JEE Main · 2005 · 08 May 2005 · Offline · Single correct option

Practise more: all JEE Main PYQs on Chemical Kinetics →

More JEE Main questions on Chemical Kinetics

Pre-exponential factors of two different reactions of same order are identical. Let activation energy of first reaction exceeds the activation energy of second reaction by $20 kJ mol^{- 1}$ . If $k_{1}$ and $k_{2}$ are the rate constants of fir …
JEE Main 2026View solution →
A → products (First order reaction).

Three sets of experiment were performed for a reaction under similar experimental conditions.
Run $1 \Rightarrow 100 mL$ of 10 M solution of reactant A
Run $2 \Rightarrow 200 mL$ of 10 M solution of reactant A
Run …
JEE Main 2026View solution →
The temperature at which the rate constants of the given below two gaseous reactions become equal is
____ K. (Nearest integer).
$X ⟶ Y k_{1} = 1 0^{6} e^{\frac{- 30000}{T}}$ …
JEE Main 2026View solution →
Decomposition of A is a first order reaction at $T (K)$ and is given by $A (g) \to B (g) + C (g)$ . In a closed 1 L vessel, 1 bar $A (g)$ is allowed to decompose at $T (K)$ . …
JEE Main 2026View solution →
Correct statements regarding Arrhenius equation among the following are :
(A) Factor $e^{- Ea / RT}$ corresponds to fraction of molecules having kinetic energy less than Ea.
(B) At a given temperature, lower the Ea, faster is the reaction.
(C) Increase in tempe …
JEE Main 2026View solution →
Consider $A k_{1} B$ and $C k_{2} D$ are two reactions. If the rate constant $(k_{1})$ of the $A \to B$ reaction can be expressed by the following equation …
JEE Main 2026View solution →