Which two countries lie along korea's northern border?

When a rock is mechanically weathered, the surface area of the rock is increased, which allows a greater amount of chemical weathering to occur. the surface area of the rock is increased, which hinders chemical weathering. the volume of the rock is decreased, which hinders chemical weathering. the volume of the rock is increased, which allows a greater amount of chemical weathering to occur. the surface area of the rock is decreased, which allows a greater amount of chemical weathering to occur