Answer: 430 nm.
Explanation:
The relation of wavelength and frequency is:
Formula used :
where,
= frequency =
= wavelength = ?
c = speed of light = 
Now put all the given values in this formula, we get

Thus the wavelength (in nm) of the blue light emitted by a mercury lamp is 430 nm.
The trampoline one would be for the elastic answer, the chemical one would be for the chemical answer, and the last one would be for the gravitational one :)
because the building are weaker and they are most likley to fall
Answers
1. cumulus ⇒ b. look like pieces of cotton in the sky
2. altostratus ⇒ c. resembles an overcast sky; layers of gray or white clouds
3. cirrus ⇒ a. look like wispy feathers high in the sky
4. nimbostratus ⇒ E.dark, thick-layered clouds; rain's coming
5. fog ⇒ d. clouds nearest Earth's surface
Answer:
0.39 m/s²
Explanation:
From the question,
a = v²/r.................... Equation 1
Where v = velocity, r = radius.
Given: v = 222 mi/h = (222×0.44704) m/s = 9.83 m/s, r = 820 ft = (820×0.3048) m = 249.94 m.
Substitute thses values into equation 1
a = 9.83²/249.94
a = 96.63/249.94
a = 0.39 m/s²
Hence the acceleration is 0.39 m/s²