What's the next in the series?

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

There are three identical triplets sisters. Demi is the oldest of them all and she always speaks the truth. Diana is the next one who is a liar always. Drew, the youngest of them all speaks both truth and lies randomly.

On a rainy day, a family friend Victor visited them. Since there were starkly identical, he was not able to recognize them. Thus to clarify, he asked one question to each one of them.

He started with the one standing on the left and asked, 'Which sister is in the middle of you three?' She answered, 'That's Demi.'

Then, he asked the one standing in the middle, 'What is your name?' She answered, 'I am Drew.'

Finally, he asked the one standing on the right, 'Who is standing in the middle?' She answered, 'She is Diana.'

Victor was left baffled. He asked the questions three times and received different answers every time.

Can you tell who was who?

What is the difference between a jeweller and a jailer?

You have three orange, two pink and five purple balls in the drawer beside your bed. There is no electricity and the room is entirely dark. How many balls must you take out to ensure at least one ball of each colour at least?

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

I am five letter word that is under you.
If you remove my 1st letter, then I am over you.
If you remove my 1st and 2nd letters then I am all around you.

Who am I?

A mile-long train is moving at sixty miles an hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?

Which Burger Is Different in below image?

You order chicken wings at KFC in the boxes of 6, 9 and 20. What is the largest number of wings that you cannot obtain by buying in any combination of the boxes?

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?