बायोगैस का कैलोरी मान (calorific value) आमतौर पर लगभग कितने किलोकैलोरी प्रति घन मीटर (kcal per cubic meter) होता है?

Prolonged exposure to extreme cold temperatures may result in tissue damage known as frostbite, which is categorized as a:

In the context of ecosystem energy dynamics, which of the following expressions correctly defines Net Primary Productivity (NPP)?