Which number should replace the question mark?

What do you answer even though it never asks you questions?

Astrology starts with the alphabet A, Biology starts with B, Psychology with P and Limnology with L.

Can you find an "ology" that begins with a P?

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?

_ _ _ IE _ _
_ _ _ IE _
_ _ IE _ _
_ _ IE _
_ _ _ _ IE

Like you see, some letters have gone missing from these words that contain the IE pair at some or the other place. The letters that will be used to fill the blanks are given below. Use them and form meaningful words. Can you do that?

A, C, D, F, H, K, L, M, N, N, O, R, R, S, S, S, T, T, Y and Y.

Why do you find that most of the buildings are deprived of the 13th floor?

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

John said, "If yesterday was tomorrow, today would be Friday."

When did John make this statement?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

You can find some missing letters in the picture. By placing two particular letters in the spaces, you can form a nine lettered word beginning from one of the corners and going clockwise direction to the middle. Can you find out the letters and the word?