What goes up but never comes down?

There is a brick of gold and a brick of iron in a boat (both 10-inch blocks), if they are both dropped into the water which will make the water level higher?

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

You have two buckets of 11 liters and 6 litres.
How can you measure exactly 8 litres?

A patient was diagnosed with some ailment. He was given five different tablets to take at night at an interval of 15 minutes.

How long will it take the patient to consume all the five tablets?

What is wrong in the below Picture?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

What jumps when it walks and sits when it stands?

A red house is made out of red bricks. A yellow house is made out of yellow bricks. And, a blue house is made out of blue bricks. So, what is a greenhouse made of?

Can you place six X (crosses) in below board without making three in a row in any way ?