What does the following BrainBat signifies?

ABCDEFGHIJKLMNOPQRSTUVWYZ

QQQQQQQQQQQQQQQQQQQQQQQQQ.

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

What is the coolest letter in the alphabet?

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?

How many times do a clock's hands overlap in a day ?

Why is the Hole below a Lock?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

You are given a cube that is made with the help of 10x10x10 smaller cubes summing up to a total of 1000 smaller cubes. You are asked to take off one layer of the cubes.
How many remain now?