Question

X‑rays are part of the electromagnetic spectrum.
Hospitals use X‑rays for medical imaging.
(a) (i) State the speed of X‑rays.
                                                 …………………………………………… m/s 
(ii) An X‑ray machine in a hospital uses X‑rays with a wavelength of 2.0 × 10^–11m.
Calculate the frequency of these X‑rays.
                                                frequency = ……………………………………………. Hz 
(b) Hospitals also use ultrasound waves for medical imaging.
(i) Ultrasound waves are high frequency sound waves which are longitudinal.
X‑rays are transverse waves.
Complete the sentences to describe the nature of longitudinal and transverse waves.
Longitudinal waves are produced by vibrations that are
                …………………………………………………….. to the direction of energy transfer.
Transverse waves are produced by vibrations that are
                ……………………………………………………… to the direction of energy transfer.
(ii) During an ultrasound scan, ultrasound waves travel through gaseous air, solid bone and liquid blood.
Sound waves, including ultrasound waves, travel at different speeds in gases, solids and liquids.
Place the speed of sound in a gas, a solid and a liquid in order from fastest to slowest.
       fastest …………………………………………………

       slowest …………………………………………………

(c) Hospitals use radioactive tracers such as technetium‑99 (99 43 Tc) for medical imaging.
(i) 99 43 Tc has a half‑life of 6 hours.
Calculate the percentage of 99
43 Tc remaining in a sample after 24 hours.
                                              percentage remaining = ………………………………………………% 
(ii) 99 43 Tc is produced in hospitals from molybdenum‑99 (99 42Mo).
Use the correct nuclide notation to complete the decay equation for molybdenum‑99.