Transform the word THINK into BRAIN while changing only one letter at a time in a manner that each of the word in the process is a real word!!!

What do you answer even though it never asks you questions?

I want to fill my bucket using both cold and hot water.
I have two taps for both cold and hot water. The hot water tap fills the bucket in exact 6 hours and the cold water tap fills the bucket in exact 4 hours.
I turn both of them simultaneously but I forgot to turn off another tap which removes the water out of the bucket. This tap can empty the bucket in 12 hours.

How Long will it take to fill the bucket?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

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

You can see it everyday, But cannot touch it at will. What is it?

By using 'because' continuously three times, can you make an English statement ?

What is the word or phrase below?
R | E | A | D

Can you find out what is missing?

1 3 5
2 4 ?

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

Look at the picture and find out which square is not linked with any of the other squares.