Virus vs bacterium: what's worse?

What's an exponential dilemma? Why do copper bangles make your wrist go green? What causes hot flushes associated with menopause? Can drinking water make you breathless? Which is worse, viruses or bacteria? Why put power points at floor level? Can ketamine be used to treat mental illness? And why don't the bubbles from cracked joints cause an air embolism? Want to find out? Why not Ask! The Naked Scientists: join Dr Chris and Kieno Kammies for the answers...