You must open resource monitor(Start>accessories>system tools>resource monitor or task manager>performance>resource monitor). Click on the cpu tab and you should see all your cores on the right side. If the core is parked you should see 'parked' ,eg 'Core 1 - Parked', beside you core name. If you don't see any 'parked' means none of your cores are parked.
But i doubt you will see core parking on i5's, i'm not sure but its mostly on hyper threaded cpu's, like i7's.