How is the moon similar to a dollar?

You can hear me, but you can't touch or see me.

What am I?

Count the squares in the matchstick puzzle below?

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?

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

I have an eye but still cannot see.

Who am I?

I am dry when I go inside, but wet when I am pulled outside.
The longer I am inside, the stronger I get
When I am completely out, I am wet and I literally sag
Who am I?

A man plots the murder of his wife. His plan is full proof. Nobody saw them leaving their house. He stabbed her with a knife while driving. She died on the spot. He threw her body in a valley. He threw the knife carefully wiping his finger prints on a random garbage bin. Then he went back to his home and no one was watching him this time as well.

After an hour, he was called by the local police department who informed him that his wife was murdered. They asked him to reach the scene of crime immediately. But as soon as he arrived at the crime scene, he was arrested by them.

How did the police know that he himself is the murderer?

The following four words might seem abrupt to you. But you can make them meaningful by just adding vowels.
RDSH
GGPLNT
TMT
NN

Hint: All of them are vegetables.