Oct. 7: US First Lady Michelle Obama has been named the most powerful woman in the world beating corporate honchos like India-born Pepsi Co chief Indra Nooyi and heads of state like the Queen of England to occupy the top slot in Forbes magazine’s annual list. Michelle, 46, ranked number one in the overall list of “The World’s 100 Most Powerful Women” 2010 released on Thursday. She ranked No. 1 in “political” category too.Kraft Foods chief executive Irene Rosenfeld ranked second and is followed by media mogul Oprah Winfrey in the third spot and German Chancellor Angela Merkel who ranks fourth. Nooyi, ranked 6th on the list.