Challenging mind puzzles

It's time to exercise your brain! See if you can crack them all!

Challenge 1

Fill in the letters to form English words. The number of blanks is the number of missing letters. Eg. the answer to ch_ _ch is church.

ch_ _ch

in_ _ _in

on_ _on

to_ _to

le_ _ _le

er_ _ _er

und_ _ _ _ _und

ing _ _ _ing

Challenge 2

Form English words for the below five puzzles by filling in the SAME letters in the same order.

sc_ _ _

t_ _ _

g_ _ _

sp_ _ _

b_ _ _

Challenge 3

What 2 symbols come next?

Challenge 4
What is the next line?

Challenge 5

What is the next number and why?

8, 5, 4, 9, 1, 7, 6, 3, 2, _