Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

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

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?

Name a key which is hardest to turn.

What does this rebus mean?

O
N
C
E
TIME

Suppose we lay down two cups in front of you. One of the cups is filled with tea and the other one with coffee. Now we ask you to take a spoonful of tea and mix it with the coffee. At this moment, the coffee cup has a mixture of tea and coffee. You have to take that mixture (spoonful) and add it back to the tea.

Can you now tell if the cup of coffee has more tea or the cup of tea has more coffee?

You can see three almost identical images below. Can you spot the odd one out from them?

John and his wife were living in a rural place. On a particular day, John's wife fell ill and he called the local doctor. When the doctor picked up, he said, "Doctor, my wife is ill. She might have appendicitis."

"This can't be possible! I took out her appendix two years ago myself," the doctor explained.

When diagnosed, John's wife was found to have appendicitis. How can this be possible?

The peacock is a bird that does not lay eggs. How do they get baby peacocks?

Can you find the key in the picture below?