Spot what is wrong here in below Picture?

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

Solve the equation by replacing the alphabet with numbers.

MOM + MOM + NO = BOOK=

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

One day, all the courtiers from Akbar's court were gathered in the assembly hall when one of them told the Emperor that all his valuables had been stolen by a thief the previous night.
This shocked the Emperor to his core as the place where that courter stayed was the most secured in the kingdom. The Emperor thought that it is not at all possible for an outsider to enter into the courtier's house and steal the valuables. Only another courtier could commit this crime. He quickly called Birbal to identify the thief.
Birbal thought for a while and successfully solved the mystery by identifying the thief in just one statement.
What did Birbal say?

With the help clues provided in the image, can you find the 5 digit key?

I noticed one of the words in the oxford dictionary is spelled incorrectly. What about you?

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

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?

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