Radiography techs are trained to operate medical equipment that uses X-rays and other types of radiation. Ultrasound techs, referred to professionally as diagnostic medical sonographers, operate equipment that uses high-frequency sound waves to create images.
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Answer:

Explanation:
Hello there!
In this case, according to the given information, it turns out firstly necessary to write out the described chemical reaction as shown below:

Now, we set up the expression for the calculation of the standard free energy change, considering the free energy of formation of each species, specially those of H2 and F2 which are both 0 because they are pure elements:

Regards!
No, since they are the strongest type of ray only elements that are dense can block them.
The correct answer is C: the alkaline earth metals!