QQQ has huge tech exposure, but it is not a 'tech fund' in the pure sense either. The fund's arcane weighting rules further distance it from anything close to plain vanilla large-cap or pure-play tech coverage.
During the time when Earth was forming and was in a molten state, heavy materials like iron and nickel sank to the center of the Earth's mass and lighter materials floated to the surface of the mass. The very center of what we call the core, is solid in the middle because of the increased pressure in that region.
In its first few million years, the Earth was a hot, semiliquid mass that separated into layers according to the density of each layer, a process similar to what happens when oil floats on water. Most, though not all, of the heavy elements sank to the center while the lighter ones rose to the top.