What's the next in the series?

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

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.

Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

Which of the below owl is odd one out?

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

How many letters are in the alphabet?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?

A man is sitting in a pub feeling rather poor. He sees that the man next to him is extremely rich. He turns to the rich man and says to him, 'I have an amazing talent; I know almost every song that has ever existed.'
The rich man laughs.
The poor man says, 'I am willing to bet you all the money you have in your wallet that I can sing a genuine song with a lady's name of your choice in it.'
The rich man laughs again and says, 'OK, how about my daughter's name, Joanna Armstrong-Miller?'
The rich man goes home poor. The poor man goes home rich.

What song did he sing? A man is sitting in a pub feeling rather poor. He sees the man next to him pull a wad of £50 notes out of his wallet. He turns to the rich man and says to him, 'I have an amazing talent; I know almost every song that has ever existed.' The rich man laughs. The poor man says, 'I am willing to bet you all the money you have in your wallet that I can sing a genuine song with a lady's name of your choice in it.' The rich man laughs again and says, 'OK, how about my daughter's name, Joanna Armstrong-Miller?' The rich man goes home poor. The poor man goes home rich. What song did he sing?

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.