https://en.wikipedia.org/wiki/List_of_countries_whose_capital_is_not_their_largest_cityYou might want to update this quiz using this because there asre a couple of countries you have missed out.
All of the countries I didn't use that are included on that Wikipedia page have capitals included in, or part of, the urban area of their countries largest city.
The urban area of Veletta is larger than any other urban area in Malta. Also, although Washington D.C.'s city proper population is relatively small, its urban area population is the fourth largest in the United States (San Francisco is just a little bit smaller)