Pakistan is our dear country and as you said NTS is national testing service so they will defiantly ask you questions like this and here's the answer:
Pakistan is the country created for the purity and Choudhry Rahmat Ali coined this name in 1933.
Pakistan is one name generated with two names "Pak and Istan" in Persian and Urdu Pakistan means Pure-Land (land of the pure).
Word pāk means Pure in Persian and word istān means Place of or Land of in Pashto language, so ultimately it becomes land of purity "Pakistan".
As we (Pakistanis) describe it we say Pakistan means LaIlaHaIlAllah and in grammar it means Peace Land.
The final thing is Pakistan is for pure people and the name itself says we are not mixed with any black heart people.
Pakistan is love and we love who lives in Pakistan. Thanks for asking.