Hi Priyanka,
What you can do is, you can use the ‘Constraint by ’ feature in the reference selector, or you can visit my blog, by clicking on the link below,
https://medium.com/mendix/easily-create-custom-dependent-drop-downs-in-mendix-343a38b8041d
where I explained how to set interdependencies between the dropdowns,
Now, on the refresh of the page, you can check in the City dropdown, whether the country is chosen or not,
if the country is chosen, then you can set the City and show it to the User,
Let me know, if you have any issues,
Hope it helps!