Which Number is the odd one out?

A) 7145
B) 2716
C) 5321
D) 4135

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

The horse jumps over the king.
Strangely there is absolutely no scratch on him.

Can anyone explain, how is this possible?

Two trains start at the same time, one from Bangalore to Mysore and the other from Mysore to Bangalore. if they arrive at their destinations one hour and four hours respectively after passing one another, how much faster is one train running than the other?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

Find the combined weight of the Cat, Dog and Rabbit in the given picture.

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

Which country gets ill every time?

What happened when the wheel was invented?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?