What gives a flame its colour, and what is the hottest part? What limits the height of a skyscraper? How does post-exposure prophylaxis for HIV work? How do they put the lines on a clay tennis court? Why do some songs cause goose-pimples? Why are some people better at withstanding temperature extremes? And can lightning be collected as a power-source? Join us for the answers and some lively chat from Talk Radio 702, South Africa.