Need help with characteristics of numbers?

Question

1.) Sam organized 16 numbers according to a particular characteristic as shown below. None of the members in one of these sets could have been placed with another set accordng to the characteristic Sam used for his organization. He could have put 8 in which set?

Set A = {1, 2, 6, 10}
Set B = {4, 5, 9}
Set C = {3, 7, 50, 60}
Set D = {11, 12, 20, 30, 80}

2.) All of the numbers in set Q have a particular characteristic that none of the numbers in set M have. Which of the following numbers does not have this characteristic?

Set Q = {425.1, 23, 529, 4320}
Set M = {395, 36.7, 43.29, 6.2}

Answer 1

1) Set A = numbers with 3-letter names
Set B = numbers with 4-letter names
Set C = numbers with 5-letter names
Set D = numbers with 6-letter names
Since "eight" has five letters, 8 belongs in set C.

Can't think of anything for number 2, sorry.