We were in physics a few days ago and we were studying radioactivity, our teacher mentioned that even bananas contain radioactive elements. So I was wondering, how many bananas do you theoretically have to eat to get radiation poisoning?

At school we have been learning about metals reacting with acid.  I had a look at the periodic table and I saw that pottasium (K)  was an alkali metal.  I also knew that bananas are an excellent source of pottasium.  So why, when I eat a banana, does the hydrochloric acid in my stomach not react and make me explode?

Felix, 11, Norwich