What does does this rebus picture means ?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

You are given four results as below:
1111 = F
2222 = E
3333 = T
Then, can you find out how to code 4444?

The cream is heavier than Milk. True or False?

Rearrange the letters in "new door" to make one word.

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

As shown in the image, the nine Dogs are square fenced. By constructing just two square fences can you make sure that two Dogs cannot meet each other without crossing the fence?

There once were seven dwarfs who were all brothers. They were all born two years apart. The youngest dwarf is seven years old. How old is his oldest brother?

You have three orange, two pink and five purple balls in the drawer beside your bed. There is no electricity and the room is entirely dark. How many balls must you take out to ensure at least one ball of each colour at least?

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