What is the Surname of Barbie Doll?

In a concert, Christina is performing a dance show with her group.
At 10:00, she and her crew were dancing in an absolutely straight line. At that time Christina was standing in 4th position from both the front and back end of the row.

What was the size of her crew?

What's a single-digit number with no value?

What do you think with the below Picture ?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

You can see three almost identical images below. Can you spot the odd one out from them?

The picture shows the dice results in each couple of throws. If they are actually following a pattern, can you find out the missing one?

If eleven plus two equals one, what does nine plus five equal?

What is red and smells like blue paint?