What is the longest word in the dictionary?

What does the following BrainBat signifies?

ABCDEFGHIJKLMNOPQRSTUVWYZ

QQQQQQQQQQQQQQQQQQQQQQQQQ.

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?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

I have teeth but i don't bite. Who Am I ?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

Buy me, smell me or deliver me, I do not change.

Who am I?

You have two rectangular wires.

Both of them have property that when you light the fire from one end , it will take 60 minutes to get completely burn.

However, they do not burn at consistent speed (i.e it might be possible 1st 20% burn in 50 minutes and 80% can burn in 10 minutes).

So how could you measure 45 minutes ?

Remove two matchsticks to make the below equation correct.

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?