वाहनों के धुएँ से निकलने वाली वह कौन सी मुख्य विषैली गैस है जो वायु प्रदूषण का एक प्रमुख कारण 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?