Answer: Option [B]Rift valley is formed due to Faulting. A rift valley is formed mainly due to the subsidence of the floor of a river valley. A rift valley is formed on a divergent plate boundary, a crustal extension or spreading apart of the surface, which is subsequently further deepened by the forces of erosion.
Answer: Option [D]Exogenic processes include geological phenomena and processes that originate externally to the Earth's surface. They are genetically related to the atmosphere, hydrosphere and biosphere, and therefore to processes of weathering, erosion, transportation, deposition, denudation etc.
Answer: Option [A]The work of river in middle course is mainly Erosion. The middle course of a river has more energy and volume then in the upper course. The gradient is more gentle and lateral (sideways) erosion has widened the channel. The river channel has also become deeper. Meanders are typical landforms found in this stage of the river.
Answer: Option [A]Mass of the earth is estimated to be 5.9722×1024 kg.
Answer: Option [A]Prime Meridian passes through Greenwich. Any line of longitude (a meridian) can serve as the 0° longitude line. However, there is an international agreement that the meridian that runs through Greenwich, England, is considered the official prime meridian.