Answer:
Advantages: Very sturdy, can have several cracks in structure before breaking
disadvantages: best for short distances, not attractive, hard to maintain
It depends on the direction in which the shell is launched. The time can be anything from 3.6 seconds to never.
Impermeable is a substance that is water proofed e.g glass, aluminium e.t.c <span />
Although X-rays have many benefits, they can be dangerous to human health because they are short wavelength, high frequency, with photons sufficiently energetic to damage DNA molecules.
