Facebook chief executive Mark Zuckerberg testified before Congress in response to the privacy scandal engulfing his social network. The 33-year-old faced questions from a joint hearing of the US Senate's commerce and judiciary committees. In his opening statement, he apologised, saying: 'We didn’t take a broad enough view of our responsibility, and that was a big mistake. It was my mistake, and I’m sorry. I started Facebook, I run it, and I’m responsible for what happens here'