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.
Now click on the executable (EXE) file to install the portable VirtualBox. 2. Now you have VirtualBox installed, go ahead and create new virtual machine by running the VirtualBox. 3. On new virtual machine, you need to select or name machine as Windows 7. Then select memory as 1024MB and disk storage around 20GB.4. Now you will have to locate the Windows 7 installer (DVD or setup file saved on computer). VirtualBox will start installing Windows 7 on USB drive.5.. Once Windows 7 installation completes, you can detach USB drive safely from your computer. Done. Now you can just plug your USB Flash Drive on any computer and run Windows 7 over there. For simple use, I recommend Windows 7 Home Basic or Home Premium edition.