What is always in front of you but can’t be seen?

You walk into a room where there are three primates held in their respective cages:
1) A lion who is eating the flesh of a goat.
2) An orangutan who is playing with blocks.
3) A donkey who is sitting idle.

Who is the most intelligent primate in the room?

What happened when the wheel was invented?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

When it's bad luck to meet a black cat?

Solve the below puzzle by replacing the question mark with the correct number.

3 6 12

4 8 16

5 10 ?

A sundial has the fewest moving parts of any timepiece. Which has the most?

When you stop to look, you can always see me. But if you try to touch me, you can never feel me. Although you walk towards me, I remain the same distance from you. What am I?

Can you count the number of blocks in the picture below?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?