As far as scientists know, the layer of the sun studied during an eclipse is composed of which atoms or subatomic particles? what is the number one mystery about this layer?

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.

The answer is    d.  central highlands

Largely uneconomic because they provide little profit or food surplusi think so

Answer india