How many times in a given day, minutes and hour clock comes in a straight line ?

I organized a small get together at my home.
In the party , i have a barrel with some whiskey in it.

Suddenly Guest 1 say 'I bet this barrel of whiskey is more than half full'.
'No, it's less than half full' Guest 2 replied.

I don't have any measuring instrument and without removing whiskey from it , how can i determine which of the guest is right ?

If an electric train is travelling south, then which way is the smoke going?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

You are confined in a room and given two metal rods. Out of these two rods, one is magnet and the other is the iron rod. They look starkly similar. You don't have any other metal object in the room.

How will you decide which one of those is magnet?

If,

6 / 7 = 2
3 / 9 = 7
8 / 2 = 6

Then

4 / 5 = ?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

Which city is three-fifths chick two third cat and 50% goat?

Two friends were betting. One said to the other, "The coin will be flipped twenty times and each time the coin lands on the head, I will give you $2 and each time it lands on the tale, you will give me $3." After flipping the coin twenty times not a single penny was exchanged among them.

How many times did the coin land on heads?