Is it hard to learn an instrument as an adult?  

I don't think so but I also think it depends on the person. It is considered easier for a child because you have more time as a child to practice and your brain is better able to remember finder placements. 

What do you want to learn? I think that factors in. If you are going to try something like the piano, your chances are high of learning it but if you are going for something like the drums or a violin, it might be a struggle!! 

Maybe? I can't say I have ever done it. I know how to play a few but I learned as a young child so I really can't say if it would be hard or not now that you are an adult.

I don't think age matters, it depends on the individual. Some people can pick up things and learn them faster than others. This is often how children are as well. 

It can be but if you stick with it and continue practicing, you will eventually learn to play. Anyone can learn to play any instrument but it takes skill to master them.

It can be harder to learn an instrument as an adult, since you may have less time and patience than when you were younger. However, it is still possible to learn an instrument as an adult if you are willing to put in the effort. There are many resources available to help adults learn instruments, so don't be discouraged. You can do it!

It's not hard much just need more time for studying

It is hard to master but I think most can be learned at any age. I have a friend who learned a few in her adult life and she does well!