समुद्र तल की वह क्षैतिज सतह जिससे ऊँचाई और गहराई दोनों की माप होती है, क्या कहलाती 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?