LONDON- MQM’s senior leader Farooq Sattar has said that extremism and terrorism are the biggest challenges being faced by Pakistan. Speaking at an Iftar dinner in London today, Sattar said that there was dire need to show national unity and economic prosperity to stabilize Pakistan. “Everyone chants slogans of revolution, but very few of them who present a practical model, can succeed,” he said. Altaf Hussain has sent people from middle class to the corridors of power, he added.