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

What do you see in the given picture?

In the image below, can you find the value of an angle(y)

Ten coins have been arranged as you can see in the given picture. In this arrangement, a triangle is formed pointing upwards. You have to invert the position of the triangle and make it point downwards while changing the position of 3 coins only. Can you do it?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1

Which famous Hollywood movie name is hidden in the below rebus?

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

Write the next letter in this sequence.
O, T, T, F, F, S, S, E, __
**Hint: It is a Number Series Puzzle