A father's child, a mother's child, yet no one's son.

Who am I?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

Which tank will fill first?

Mr. Buttons was all set to go to the village of Buttonland to meet his friend. So, he packed his bags and left for the village at 5 in the morning. Upon travelling on a road for miles, he came across a point where the road diverged into two. He was confused on which road to take. He gazed around and he saw two owls sitting on a branch. He thought he could ask for directions for the village from the two owls. So he went to the tree. There he saw a sign which read, "One owl always lies, and one is always truthful. They both fly away if you ask them more than 1 question."
Mr. Buttons was caught in the dilemma of what to ask? And from which owl to ask, since he only had one question. What should Mr. Buttons ask?

What do you get if you add 2 to 100 four times?

Can you replace the question mark with the correct letter?

6 + 6 + 6 = N
7 + 7 + 7 = E
8 + 8 + 8 = R
0 + 0 + 0 = ?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

When 99 is considered higher than 100?

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?