Questions

Yes, single thread module

User thread

Kernel thread

Static RAM: no refreshing, 6 to 8 MOS transistors are required to form one memory cell, information stored as voltage level in flip flop. 

Dynamic RAM: refreshed periodically, 3 to 4 transistors are required to form one memory cell, information is  stored as a charge in the gate to substrate capacitance.

Groundwater is all the water that has penetrated the earth's surface and is found in one of two soil layers. The one nearest the surface is the "zone of aeration", where gaps between soil are filled with both air and water. Below this layer is the "zone of saturation", where the gaps are filled with water.