How to tell between que and quien in spanish

Que generally means what (refers to an object or place) while quien generally means who (refers to a person). Even though they both refer to nouns, they refer to different types of nouns

Hope this helps

1one sharp difficulty presented itself. in the intervening twenty-five years my name had become reasonably well known.2 this being so, my trip demanded that i leave my name and my identity at home.3 i had to go alone and i had to be self-contained, a kind of casual turtle carrying his house on his back.4 with all this in mind i wrote to the head office of a great corporation which manufactures trucks.

Procedural is the answer.  hope that ! : )