True or false.If false, please explain.

5. {0} ~ {0} [ Select ] 6. If Aang, Katara, Zuko, Toph, and Sokka sit down in a row, then there are 20 arrangements possible given that Katara sits between Aang and Zuko (but not necessarily adjacent to either of them). [Select ] 7. If the intersection of two sets is countable, then each set is also countable. [ Select ] 8. The sequence 27 3 3 -9 21 20 ' 4' 20 20 20 ... is a geometric progression. [ Select ] 9. There are 5,448,643,200 possible ways of arranging the characters of the word COST-EFFECTIVE in a row? [Select ] P