तापीय ऊर्जा (Thermal power) को नवीकरणीय ऊर्जा स्रोत क्यों नहीं माना जाता है?

What is considered the primary source of energy for most ecosystems on Earth?

Which form of energy is primarily caused by the gravitational pull of the Sun and the Moon on the Earth?

Arrange the following coal/fuel types in the increasing order of their heat content (calorific value): (A) Peat (B) Lignite (C) Anthracite (D) Bituminous (E) Sub-bituminous