This is a very profound question with very many possible answers. We could look over the long term, and show how science has been beneficial in any specific area, such as curing disease and famine, providing us with communication and transportation, or allowing us the luxuries and comforts of modern life. However, let's look at this in a broader picture by thinking of what science is.

Science is just a system to figure out how something works, and thus how we can improve it. Science is a system of learning. So when you ask, "how science is beneficial to the nation," a similar question might be,"how is learning beneficial to you?" If you were to stop learning, what would happen? You likely wouldn't notice a change right away, but because the world is always changing and everyone else is always learning, you'd probably fall behind everyone else very quickly, and you wouldn't be able to function very well.

Similarly, science is beneficial to the nation because it allows us to improve, to adapt, and to learn. Additionally, when you learn, you may learn of new ways to do something, or of new things that exist. Similarly, science also creates a lot of new things that change the way the nation works, and how we relate to the world. You don't need to look further than your electrical socket, as we can't even imagine a world without electricity anymore.