पास आती हुई रेलगाड़ी की सीटी की आवृत्ति या तीक्ष्णता बढ़ती जाती है, ऐसा किस घटना के कारण होता है?

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?