One third is solid, the core.
Two thirds is liquid, the outer core.
The hard crust on the outside is 0.1% of the total mass.
The core is at a temperature of over 10,000 degrees, but under so much pressure that stays solid in the form of a massive crystals in a high pressure form, a hexagonal centered packing array.
Rotation of the outer core fluids cause magnetic fields, and they are transduced by the crystalline core as a kind of natural solenoid.
The earth has lost half of the gravitational and radiaoactive heat it had when it first formed (apart from the episode where the moon was formed by a collision) and the remaining heat is now generated by radioactive decay of remaining long halflife isotopes. The Al26 has long gone, the heat is now mainly from K40 (potassium), uranium and thorium.
The core will slowly grow as the planet cools further, until one day the magnetic fields will switch off.
All planets have molten cores, and so does Pluto. Even our moon is suspected to have a molten core.