The activation energy for the acid hydrolysis of sucrose is 6.22 kJ mol−1. What is the activation energy when sucrose is hydrolysed by the enzyme sucrase?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 2.15 kJ mol−1
Enzymes are biocatalysts. Like chemical catalysts, they reduce the magnitude of the activation energy. For the hydrolysis of sucrose, the activation energy falls from 6.22 kJ mol−1 with acid to only 2.15 kJ mol−1 with the enzyme sucrase, about one-third of the value with acid.
NCERT (2026-27 edition):
10.3.1 Mechanism of Enzyme Action – “Similar to the action of chemical catalysts, enzymes are said to reduce the magnitude of activation energy. For example, activation energy for acid hydrolysis of sucrose is 6.22 kJ mol–1, while the activation energy is only 2.15 kJ mol–1 when hydrolysed by the enzyme, sucrase.”