What has many keys but can’t open a single lock?

Find out the missing number in the picture attached:

Two-person want to cross a river. Only one boat is present on the riverside that can carry only one person at a time.

However, they still manage to cross the river. How is it possible?

Dwayne Johnson was running away with the loot from a heist in his car along with Vin Diesel. One tire was punctured and he dropped down to replace it. While changing the wheel, he dropped the four nuts that were holding the wheel and they fell into a drain. Vin Diesel gave him an idea using which they were able to drive till the rendezvous point.

What was the idea ?

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

Find the missing letter in the last circle logically in the given below picture.

The cream is heavier than Milk. True or False?

I have branches, but no fruit, trunk or leaves. What am I?

Replace the question mark with the number below given a simple math problem.

Consider this: Arnold Schwarzenegger has a big one. Michael J. Fox has a small one. Prince doesn’t have one. The Pope has one but never uses it. Bill Clinton has one and uses it all the time. What is it?