Answer:
Frequency, 
Explanation:
Given that,
The wavelength of the x-rays, 
We need to find the frequency of an x-ray. All electromagnetic wave travel with a speed of light. It is given by the formula as :

f is the frequency

So, the frequency of an x-ray is
. Hence, this is the required solution.
Answer:
the answer to the question is indeed B
Answer:
Momentum, 
Explanation:
Given that,
Mass of a mosquito, m = 0.000015 kg
Velocity of the mosquito, v = 5.2 m/s
We need to find the momentum of the mosquito. The momentum of an object is given by :
p = mv
Put all the values in the above formula.

So, the momentum of the mosquito is
.
Answer:Transformer
Explanation:All the other devices generate their own electricity apart from power line and Transformer, power line just carries electricity. A transformer can be used to step up or step down voltages from a source.
It depends on what they are