Cristina was born in 1888. She just had her 30th birthday today how did that happen?

During which month do people sleep the least?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?

I am a three digit number.
My tens digit is five more than my ones digit.
My hundreds digit is eight less than my tens digit.
What number am I?

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

It's a 7-letter word.
If we remove 1 letter from it, it remains the same.
If we remove 2 letters from it, it remains the same.
If we remove 3 letters from it, it remains the same.
If we remove all the letters from it, still it remains the same.
What is it?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

Three playing cards in a row. Can you name them with these clues? There is a two to the right of a king. A diamond will be found to the left of a spade. An ace is to the left of a heart. A heart is to the left of a spade. Now, identify all three cards.

In the below-given picture of a pretty girl, there is something wrong. Can you find out what it is?

What's the only room from which no one can enter or leave