I travel all around the world but always stay in the corner. What am I?

I can turn polar bears white.
I can make anyone dance.
I can make everyone cry
I can make your hands clap
I can make you thin.
I can make you smile.
I can make you smile

Can you guess the riddle?

If 21x = 79x, what is the value of x?

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

The average age of 10 members of a committee is the same as it was 4 years ago, because an old member has been replaced by a young member. Find how much younger is the new member ?

Can you find a number that lies one third of the distance between 1/3 and 2/3?

What comes
Once in a Year
Twice in a Month
4 times in a Week
6 times in a Day

One night, a woman receives a call from the police. They tell her that her husband was murdered and that she should come to the crime scene as soon as possible. The woman drops the phone, shocked, and drives 20 minutes to the crime scene. As soon as she reaches the crime scene, the police arrest her and she is convicted of murder. How do the police know she committed the crime?

With pointed fangs I sit and wait; with piercing force I crunch out fate; grabbing victims, proclaiming might; physically joining with a single bite. What am I?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?