Can anyone tell me a word in the English dictionary which has a silent 'z'?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

A non-stop marathon is the shared favourite sport of three brothers.

*The oldest one is fat and short and trudges slowly on.
*The middle brother's tall and slim and keeps a steady pace.
*The youngest runs just like the wind, speeding through the race.

"He is young in years, we let him run!" the other two brothers explained, "'because though he is surely number one, he is second, in a way." Why is it?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

How can you make number one disappear by adding something to it?

I have two sand hourglasses:
1. A 7 minute one and
2. An 11-minute one.

Using just these 2 sand hourglasses, how can I measure time as 15 minutes?

He does not have any heart but still, He manages to live.
If you kill him, you will eventually die but yet you kill him.
He cannot run, who is He?

What does the below mathematical rebus mean?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

In which direction should the missing arrow point?