Hello Shashwat!

It totally depends upon you actually but usually students find maths as the toughest subject.Having maths as your strongest subject will help you to secure higher rank in JEE.

Chemistry might seem tough at first because there is too much stuff to be mugged up. However, it is the most scoring subject among all three.

It highly depends on you .

You should not neglect any subject.

All subjects are equally important.

If you like maths you might feel it easy  the same follows for all subjects. The difficulty of each subject varies person to person .

Answering your question based on general standards I would say that 

Physics is most difficult for many students 

Some struggle with maths too 

Chemistry is widely regarded as scoring subject but it depends on the practice.

Remember practicing helps you to become strong in your weak subject too