why number 8549176320 is one of a kind?

By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?

I am the largest in my family of fifty.
The youngest of our family lives separately from the rest of the family and so do I.
I am regarded as harsh and tough.
I am so large, you cut me in two equal halves,
each half would still be larger than the second largest member of the family.
Who am I?

How can you throw a ball as hard as you can and have it come back to you even if it doesn't hit anything there is nothing attached to it and no one else catches or throws it.

John went to a parrot shop in Mexico, and the parrot owner told him that his parrot is so unique that he repeats everything he hears. John got excited and immediately bought the parrot. John went home and spoke many words, but the parrot does not repeat anything.
He went again to the parrot shop and complaint to the shopkeeper, but the shopkeeper never lied. Explain?

I look at you, you look at me I raise my right, you raise your left. What am I?

ENEMY = 2 * LINK
LINK + 2 = HELL

Then what will be TAXI + HELL? Select from the options below:
a) ROTTEN
b) DANGER
c) HEAVEN
4) MORTAL

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

Three brothers Jacob, John, and James live in Mexico City. The product of the ages of these brothers is 175. Jacob and John are twins. How old is James?

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?