Here's another funny one:

Why is the Earth's interior still molten after billions of years?

The Earth's interior is not entirely molten, but it is primarily made up of hot, solid rock that is subjected to high temperatures and pressures. The Earth's core is thought to be composed of two layers: a solid inner core and a liquid outer core. The inner core is made up of mostly iron and is about the size of the Moon. The outer core is made up of a mixture of molten iron and other elements, and it is about 2200 kilometers (1367 miles) thick.

The Earth's interior is hot because of the heat generated by the decay of radioactive elements and the heat left over from the Earth's formation. This heat is sufficient to keep the outer core in a molten state, even after billions of years. The high pressure in the Earth's interior also plays a role in keeping the outer core molten, as it increases the melting point of the materials in the outer core.

The Earth's interior is also subjected to convection, which is the movement of heat by the circulation of fluids. In the Earth's mantle, convection is driven by the movement of hot, molten rock (magma) that rises up from the deep interior and cools as it reaches the surface. This convective motion helps to redistribute heat throughout the Earth's interior and plays a role in maintaining the Earth's internal heat balance.

Radioactive decay is only occurring in continental crustal rocks (Ocean crust rocks are essentially lacking in minerals that have any radioactive decay), which comprise a minor fraction of the Earth's surface layers, and absolutely can't account for the interior heat, and certainly the heat of the Earth's formation would have dissipated long, long, ago.