Why will a frog not look green under a red light

A green object would look black in a red light because coloured objects absorb all colours except the colour they are, so a green object absorbs 6 colours (red, orange, yellow, blue, indigo, violet) and reflects 1 (green). In this situation, there is no green light to reflect and it can't reflect other colours, so it looks black. :)

The gas would begin to expand, and eventually the can would burst or explode.