Answer:
b. wind waves, seiches, tsunami, tides.
Explanation:
The wavelength of water waves is calculated measuring the distances between the trough (low point) portion of a wave. Usually, the bigger the wave, the greater the wavelength.
wind waves: small waves caused by the wind. These waves tend to be small and with a short wavelength.
seiches: are usually waves on a lake or other closed water bassin. They can be pretty high from a human perspective, so they are definitely bigger than wind waves.
tsunami: we all know how big the waves of a tsunami can be, totally wiping out coastal cities they encounter, so that's pretty big waves, and big waves tend to be larger apart (so with a bigger wavelength) than smaller ones.
tides: yes, a tide can be considered as a huge wave... that's running throughout the planet. We barely see it as a wave because we can only see one wave at a time, the next wave being tens of thousands of mile away.
Set this up as
10 = 40 (1/2)t/28
and solve for t in years.
10/40 = (1/2)t/28
log(0.25) = (t/28) log(0.5)
t = 28 log(0.25) / log(0.5) years = 56 years
Test the answer:
56 years = 2(28 years) = 2 half-lives, so the remaining amount should be 1/2 of 1/2 of the initial amount, i.e. 1/4 of the initial amount, and 10 mg = 1/4 of 40 mg.
Answer:
c) The eruption at point A would be quiet because the magma that squeezes out through oceanic crust has low silica and gas content.
