At what speed should a source of sound move away from a stationary observer so that the observer perceives the apparent frequency to be half of the original frequency? (where v is the speed of sound)

Which Indian independence movement leader was primarily known for his philosophy and practice of non-violent civil disobedience?

Who gave the call for 'Do or Die' during the Quit India Movement in 1942?

Which of the following revolutionary pairs were imprisoned together in Cellular Jail and faced harsh conditions, contributing significantly to the Indian independence movement?