General knowledge always matters for you in any competitive examination like BCS job, Bank Job or any other job examinaiton. 

The people with whom you have to deal are not all in your specialty. The world is indifferent to what you prefer to study. It presents you with opportunities, and obstacles that require general knowledge to evaluate properly.

Not everything you may be interested in falls within the category of useful. Those are items like beauty, history, philosophy.If you know nothing of them, your life is empty, and gray.

General knowledge is something that really helps us to grow both on personal as well as academic level. It narrows our sense of perceiving the world, understands, and analyzes the situations better as one would without proper knowledge.

General knowledge also helps to grow your confidence level and may prove to be of some great help during some important events of our lives like interview etc.

You may start to talk to any person on any topic, but your knowledge is something that determines your conversation and your impression on the other person, a good knowledge of everything around always impress the people around you.