Pencil lead.

A bar of soap.

The answer to this admittedly lame riddle is, “No.” The reason is that the question at the very end asks if you can guess the riddle and there is nothing that satisfies the requirements above. Some say that pressure is the answer, but they can’t explain how it turns polar bears white or pancakes brown. Nothing turns polar bears white, any more than something turns a white person white, and heat makes pancakes brown, not pressure.

One of the ten people had the key to the room. He unlocked the door, except there was nobody outside of the room.

The man said, "My head will be chopped off."

Bulldoze.

One girl took the basket. She took the last apple while it was in the basket.

HIRX

The first three letters move four places forward in the alphabet, while the fourth letter moves forward five places

A strawberry.

We first look with which numbers each number can form a pair of which the sum is a square:

Number:
Number 1 Square pairs: 1+3
1+8
1+15
Number 2 Square pairs: 2+7
2+14
Number 3 Square pairs: 3+1
3+6
3+13
Number 4 Square pairs: 4+5
4+12
Number 5 Square pairs:
5+4
5+11
Number 6 Square pairs:: 6+3
6+10
Number 7 Square pairs: 7+2
7+9
Number 8 Square pairs: 8+1 Number 9 Square pairs: 9+7
9+16
Number 10 Square pairs: 10+6
10+15
Number 11 Square pairs: 11+5
11+14
Number 12 Square pairs:12+4
12+13
Number 13 Square pairs:13+3
13+12
Number 14 Square pairs:14+2
14+11
Number 15 Square pairs:15+1
15+10
Number 16 Square pairs:16+9
As can be seen, there are two numbers that can form a pair in only one way: 8 and 16. Therefore, these two numbers need to be at the start or at the end of the sequence. If we start with the number 16, the sequence follows almost automatically: 16 9 7 2 14 11 5 4 12 13 3 6 10 15 1 8. Of course, the reverse sequence is also a possible solution.

None.

He shot his reflection in the mirror.