What is the longest word in the dictionary?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

Buy me, smell me or deliver me, I do not change.

Who am I?

Which word does the below Plexor means ?

There is something which you can be arrested for attempting but not for successfully completing.

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

There's a day, that comes around once a year.
To celebrate the man, you hold dear.
He gave you life, love and will pick you up if you fall.
When it comes to guys like him, He's the best of all.
Who is he?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

A father's child, a mother's child, yet no one's son.

Who am I?

Can you name an animal whose killing cannot be performed without spilling your own blood?