What part of earth is solid and extreamly hot

Earth's interior or inner core is solid and extremely hot.

Explanation:

The studies have shown that the Earth's surface consist of four layers, to which three are solid and one liquid which is not magma but made of molten metals like iron, nickel and sulphur. The Earth's deepest layers are the huge solid iron ball which is long about 1,500 miles in diameter.

This is called as the inner core which is white hot but the pressure there is really high that the iron or any other metal cannot melt. Above the earth's inner core, we can find the outer core which is basically a shell in liquid iron.

This layer is much cooler compared to the inner core but is still more hot. It is also mainly composed of iron, but traces of other metal like nickel and sulphur is also found there.

The core inner core I believe