Answer:
See picture and explanation below
Step-by-step explanation:
In the attached picture you have the answer for this.
In the first step, we have an acid base reaction between HCN and NaOH. When this happens, its formed the following:
HCN + NaOH --------> CN⁻ + H₂O + Na⁺
As a second step, The CN⁻ attacks the carbonile group in the cyclopentane. This causes to open the double bond, and then, the Cyano enters the molecule.
The final step is another acid base reaction, where the oxygen substracts a hydrogen atom of the water in the medium, and then, the alcohol group is formed. With this step, the cyanohydrin is finally formed. See the mechanism below in the picture.
Hope this helps