When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

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.

What month of the year has 28 days?

A man calls his dog from the opposite side of a river. The dog crosses the river without a bridge or a boat and manages to not get wet. How is this possible?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

If a wheel has 54 spokes, how many spaces are there between the spokes?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

I’m tall when I’m young, and I’m short when I’m old. What am I?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

There is a five-letter word which has 3 consonants(all are same) and 2 different vowels.
Also, something wrong is associated with the word.

Can you name it?