The answer is, A. seafloor spreading occurs
frequency's unit is Hz which mean cycles per second
given frequency * wavelength = speed of wave
speed of light = 3x10^8 m/s
wavelength = 680nm = 680x10^-9 m
frequency * 680x10^-9 m = 3x10^8 m/s
frequency = 3x10^8 / 680x10^-9
= 4.41x10^14 Hz
= 441x10^12 Hz
= 441 THz
which is the frequency for red light
The time it takes for 1g of strontium-90 to decay to 250 mg is; 57.6 years
<h3>What is the half life of an element?</h3>
The formula for half life is;
A(t) = A₀ * (¹/₂)^(t/t_1/2)
Where;
A(t) is amount left after t years
A₀ the initial quantity of the substance that will undergo decay;
t_1/2 is the half-life of the decaying quantity.
We are given;
t_1/2 = 28.8 years
A₀ = 1 g
A(t) = 250 mg = 0.25 g
Thus;
0.25 = 1 * (¹/₂)^(t/28.8)
log 0.25 = (t/28.8) log (1/2)
-0.60206 = (t/28.8) * -0.3010
t = 2 * 28.8
t = 57.6 years
Read more about half life at; brainly.com/question/11152793
Answer:
A. disgust with the coercive aspects of modern educational methods
inject is pretty negative
