Question

The inversion of cane-sugar is a _____ (first/second) order reaction though its molecularity is two.

Answer 1

The inversion of cane-sugar is a first-order reaction though its molecularity is two.

$Sucrose+water\rightleftharpoons Glucose+Fructose$

In this hydrolysis reaction, both sucrose and water participate. Hence, it is a bimolecular reaction.
Since water is present in large excess, its concentration does not appear in the rate law expression.

Hence, the rate law expression is $rate=k\left[sucrose\right]$
So, the reaction is the first-order reaction.