Why Aeroplane windows are round?

Rebus Puzzle Definition: A rebus is an illusion device that uses pictures to represent words or parts of words.
What does This Rebus Puzzle Identify?

I have branches, but no fruit, trunk or leaves. What am I?

Find The Missing Number In the Sequence.
6 25 64 ? 32 1

What English word has three consecutive double letters?

What happened when the wheel was invented?

What Deficiency does the below rebus represent?

VIT_MIN

A guard is positioned at the one side of the bridge saying ‘A’. His task is to shoot all those who try to leave from ‘A’ to the other side and say ‘B’. He also need to welcome the person who comes from another side ‘B’ to his side ‘A’. The guard comes out of his post every 1 hour and looks down the bridge for any people trying to leave. You are at side ‘A’ and wish to go to another side ‘B’. you also know that it would take 1:45 hr to cross the bridge. How will you cross the bridge?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

It is always ahead of me yet I can never see it. What is it?