Questions

Yes, we know that water is a universal solvent.

Water can moderate temperature because of the two properties: high-specific heat and the high heat of vaporization.

Water is a polar molecule that has a high level of polarity and attraction to ions and other polar molecules.

Hence, all the above given options are the properties of water.

Crystal size in igneous rocks is determined by rate of cooling i.e, the time taken by magma to cool down. 

Hence, the slower the rate of cooling the larger the crystals. The faster the rate of cooling the smaller the crystals.

In communication satellite, multiple repeaters are known as Transponders.

The speed of all the electromagnetic radiation are always   same   and   equal   to   the numerical value 3 x 10^8m/sec.

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.