Seeds are living, but are "dormant" until they are in certain conditions where they can grow. You can tell if your seeds are healthy enough to germinate, or grow, or not. It is actually pretty simple! Healthy seeds (depending on size it's easier to tell) may have a shiny coating, feel firm, and some may have some healthy spots on them. If your seeds are brittle and easily breakable then they mostly probably are not healthy enough to grow plants. The color also matter; they should grey-green, grey-brown, grey, brown, or green. And another way to check is to just plant a couple!

Living seeds grow and they produce carbon dioxide, so they should produce bubbles (if very slowly).

What a great scientific question! Since seeds are a baby plant, you would need sunlight, a little bit of water, and some soil. You could then put the seeds in a little bit of soil, water them, and put them in the sun. Seeds sometimes look like they are no longer alive. They are made this way so that they have a better chance of surviving and creating new plants.