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

The Dandi March, also known as the Salt Satyagraha, was led by which influential leader?

Which act formally granted independence to India, marking the end of British rule?

Who was the key figure in establishing the Indian National Congress?