What is the word or phrase?

What number comes next in this sequence:
7 8 5 5 3 4 4 _

John Went to the nearby store in a Mall to buy something for her home. Below is the conversation between the two:

John: How much for the one?
Shopkeeper: It is $2
John: How much for the Eleven?
Shopkeeper: It is $4
John: How much for the Hundred?
Shopkeeper: It is $6.

What is John buying?

A little girl goes to the store and buys one dozen eggs. As she is going home, all but three break. How many eggs are left unbroken?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Which is Odd One Out and why?

4377

3954

9862

8454

9831

In the Chess Board picture below white army is arranged. You need to add a black army on the board such that no piece is under any threat.
Note: Army comprised of 1 king, 1 queen, 2 rooks, 2 bishops, 2 knights, and 8 pawns.

Can you find any error in the following sentence?

A taxi was standing outside a fort at night. A man came out of the fort, opened the gate and hit the taxi driver killing him instantly. He took all the money out of the meter and started running till he was caught by a local sheriff.

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

In one of the popular batman series movie "Batman Forever", there was a riddle that goes like "Tear me off and then scratch my head and I was red then and now I am back. Who am I?