Question

why is the earth's interior in most part found in solid state despite of great heat and pressure

Answer 1

Great pressure is what causes the core to behave like a solid rather than liquid. Due to the immense pressure of the upper layers of earth on core, the pressure can reach as high as thousands and thousands of tone's per square inch!!!! So this would not come to you as a shock if a semi liquid starts to behave like a solid in these conditions