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NEET 2026
Exam
NEET
Year
2026
Subject
Chemistry
Chapter
Chapter

NEET 2026 · Chemistry · Chapter

The given plot shows the variation of k versus (1)/(T) for two...

The given plot shows the variation of k versus (1)/(T) for two different chemical reactions, Reaction 1 and Reaction 2.
The given plot shows the variation of ln⁡k\ln k versus 1T\frac{1}{T} for two different chemical reactions, Reaction 1 and Reaction 2.

Based on the graph, which of the following relations is correct regarding their activation energies (EaE_a) and pre-exponential factors (AA)?

Options

  1. AEa1>Ea2E_{a1} > E_{a2} and A1>A2A_1 > A_2
  2. BEa1>Ea2E_{a1} > E_{a2} and A1=A2A_1 = A_2
  3. CEa1<Ea2E_{a1} < E_{a2} and A1<A2A_1 < A_2
  4. DEa1<Ea2E_{a1} < E_{a2} and A1=A2A_1 = A_2

Correct answer

B. Ea1>Ea2E_{a1} > E_{a2} and A1=A2A_1 = A_2

Step-by-step solution

According to the Arrhenius equation:

k=Ae−Ea/RTk = A e^{-E_a / RT}

Taking the natural logarithm on both sides, we get:

ln⁡k=ln⁡A−EaR(1T)\ln k = \ln A - \dfrac{E_a}{R} \left(\dfrac{1}{T}\right)

This represents a straight line equation y=mx+cy = mx + c, where y=ln⁡ky = \ln k and x=1Tx = \dfrac{1}{T}.
The slope of the line is m=−EaRm = -\dfrac{E_a}{R} and the y-intercept is c=ln⁡Ac = \ln A.

From the given graph, both Reaction 1 and Reaction 2 have the same y-intercept. Therefore:

ln⁡A1=ln⁡A2⇒A1=A2\ln A_1 = \ln A_2 \Rightarrow A_1 = A_2

The graph also shows that the line for Reaction 1 is steeper (has a more negative slope) than the line for Reaction 2. Let m1m_1 and m2m_2 be their respective slopes.

m1<m2m_1 < m_2

−Ea1R<−Ea2R-\dfrac{E_{a1}}{R} < -\dfrac{E_{a2}}{R}

Multiplying by −R-R (which reverses the inequality):

Ea1>Ea2E_{a1} > E_{a2}

Thus, Ea1>Ea2E_{a1} > E_{a2} and A1=A2A_1 = A_2.

Answer: Ea1>Ea2E_{a1} > E_{a2} and A1=A2A_1 = A_2
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