Brain Teasers and Puzzles 

Workings

Hint
This is quite a common list.

Answer
T.

The first letters of playing cards in descending order of value.

Workings

Hint
This is a well known nursery rhyme.

Answer
HDD.

The initial letters from the nursery rhyme, Hickory Dickory Dock.
Hickory, dickory, dock,
The mouse ran up the clock,
The clock struck one,
The mouse ran down,
Hickory, dickory, dock.

Workings

Hint
Look at the number of letters in each of the names.

Answer
No.

Those that like walking have an odd number of letters in their name.

Workings

Hint
Try this with a real board.

Answer
5.