What has many keys but can’t open a single lock?

My cousin lives in one story house in Antarctica. His house is made the of-of sandstone. what is the color of stairs?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

A Car is crossing a bridge 2 miles long. The bridge can only hold 10000 lbs, which is the exact weight of the car. The Car makes it half way across the bridge and stops. A bird lands on the car. Does the bridge collapse? Explain.

Look at me. I can bring a smile to your face, A tear to your eye, Or even a thought to your mind. But, I can't be seen. What am I?

When it is alive we sing, when it is dead we clap our hands. What is it?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

In an Art Gallary, When the clock hit 11 am, Artist hung the painting number 30. When it struck 4 pm, he hung painting number 240 and when it struck 7:30 pm, he hung painting number 315.

Can you determine, which painting number will he hang when the time is 9:20 pm?

Find three numbers such that When we multiply three numbers, we will get the prime numbers. The difference between the second and the first number is equal to the third and second.

If you had an infinite supply of water and 5-quart and 3-quart pails, how would you measure exactly 4 quarts? What is the least number of steps you need?