वायुमंडल की किस परत को आमतौर पर पृथ्वी का 'सुरक्षा कवच' कहा जाता 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?