Question

The transition zone from the outer core to the mantle is __________ and is known as the __________ discontinuity.

Answer 1

First answer is: uneven.
Second answer is: Gutenberg.
Beno Gutenberg (1889-1960) was a German-American scientist and seismologist. 
Gutenberg discontinuity separates and divides the lower mantle from the outer core of Earth. The lower mantle is solid, outer core below the line is liquid molten. 

Answer 2

The transition zone from the outer core to the mantle is uneven and is known as the Gutenberg discontinuity.

Explanation:

Gutenberg discontinuity is present in the interior of the earth at about 2900kms below the surface. In this area, there is an sudden change in the seismic waves that travel through the earth. This zone marks the boundary between the two sections of earth's interior which are mantle and the outer core.