temp segment use question

two question  about temp segment:

 1.i notice temp tablespace just have one temp segment , v$sort_segment.

so i guess does oracle temp tablespace just have only one temp segment!is  my right ?

2. guess two corruent sql ( both use select **** sort by ***),so both use temp tablespace,

does the two sql will have  contention about the only one segment ?

so sql 1 will run first ,and sql 2 will wait ,until sql 1 run  succeed, does sql 2 will begin to run ,

is my right ?