"The boy is in his cradle."
Translation:El niño está en su cuna.
I have been asking myself the same question. Maybe it's because the word "chic@" refers to a child that is a bit older, one that doesn't need a crib anymore? (-;
First of all, if it makes you feel any better, @gerardruan1, I got this wrong, too, and for the same reason. I think Maja487855 is correct. While it is true that most of the time you can swap out “niño” for “chico,” this is one of those times where it just doesn’t seem to be commonly done. I think the context — the fact that we’re talking about a cradle — eliminates “chico” as a choice.
Even so, you’re not going to find many examples of this sentence — El niño está en su cuna — but that’s more than what you’ll find for “El chico está en su cuna," which is none. If you look at the image below, which I created from a Google search of Spanish pages for "niño" and then again for "chico," maybe the reason for this will jump out at you.
If you're still wondering why you can't use "chico" in the sentence "El ___ está en su cuna," let me ask you this: Can you picture any of the "boys" that came up for "chico" still needing to use a "cuna?"