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

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

Which Travels Faster? Solve below famous picture riddle:

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

John is found dead in his office at his desk. The police have narrowed the suspects down to three people: Mrs. Jacob, John’s wife Hena and his business partner Jason . All three visited John on the day of his murder, but all three provide the police with stories of explanation as to the reason for their visit.
Police found John with his wrist watch still on his right arm, a torn up picture of his wife laying on the floor beside the trash can, and an ink pen in his right hand. On the desk, the police found a name plate, a telephone that was off the hook, and a personal calendar turned to the July 5th page with 7B91011 written on it. After examining this evidence, the police knew their suspect. Who was it ?

John killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.