Answer:
C. a disturbance that travels through a medium with a transfer of energy and without a transfer of matter
Explanation:
A wave is any disturbance that transfers energy from one location to the other via a substance called medium. It is important to note that a wave only conveys energy and not matter. For example, sound wave is a type of wave that carries sound energy from one place to another via mediums such as water, air etc.
Hence, according to this question, a wave can be described as a disturbance that travels through a medium with a transfer of energy and WITHOUT A TRANSFER OF MATTER.
A) 1.55
The speed of light in a medium is given by:

where
is the speed of light in a vacuum
n is the refractive index of the material
In this problem, the speed of light in quartz is

So we can re-arrange the previous formula to find n, the index of refraction of quartz:

B) 550.3 nm
The relationship between the wavelength of the light in air and in quartz is

where
is the wavelenght in quartz
is the wavelength in air
n is the refractive index
For the light in this problem, we have

Therefore, we can re-arrange the equation to find
, the wavelength in air:

20.4 years is 20.4/10.2 = 2 half-life cycles, which means a quarter of the starting mass or 15.2 g will remain after this time.
Adults. 18years olds and older were affected because back then only 21 years olds and older could vote but the 26th amendment changed that
Answer:
b
Explanation:
Brownian motion is the random movement of particles in a fluid due to their collisions with other atoms or molecules. ... Brownian motion takes its name from the Scottish botanist Robert Brown, who observed pollen grains moving randomly in water. He described the motion in 1827 but was unable to explain it.