So some rocks are radioactive because they have radioisotopes in their nuclei. Also they may have radon gas trapped in their crystals if they are igneous rock. They could also be radioactive due to the fact that the atom of the rock is unstable.
Connecting USB Devices Manually. Choose VM > Removable Devices to connect specific USB devices to your virtual machine. You can connect up to two USB devices at a time. If the physical USB devices are connected to the host computer through a hub, the virtual machine sees only the USB devices, not the hub.
virtual drive (virtual disk or RAM drive) What is a virtual disk? A virtual disk (also known as a virtual drive or a RAM drive) is a file that represents as a physical disk drive to a guest operating system. The file may be configured on the host and also on a remote file system.