Major product of a cyclopropanol with silver ions
A common test for haloalkanes (save fluoroalkanes) is reaction with $\ce{AgNO3}$, which initially yields the corresponding silver halide and a carbocation intermediate. The formation of the insoluble salt is the driving force for the reaction:



On a primary haloalkane this carbocation would be quenched with water, but adjacent to a three-membered ring this carbocation is primed for ring expansion. In addition to reducing ring strain, the resultant carbocation is even further stabilized by the oxygen atom:



Deprotonation gives the final substituted cyclobutanone product.