"Her son is there."
哪means where. for example "她在哪儿？"means"where is she?" 那 means there. for example "她在那儿" means "she is there."
这 means this
那 means that
哪 means which
这儿/这里 means here
那儿/那里 means there
哪儿/哪里 means where
Whats the difference between 那 and 哪? So far it appears completely arbitrary the use of one or another.
To put it very simply, 那/na4 means 'there, that etc', 哪/na3 means 'where, which etc'.
As i understand it, 那里 is simply 'there' and 哪里 is 'where'.
If you want more of a memory aid, the etymology of 哪 includes both 那 and 口, meaning a mouth or opening.
Yes. In fact, the 的 is usually dropped for family and other close relationships.