Which of the following rays/waves are used to know the growth of fetus in the womb?

Which of the following rays are used in the diagnosis of intestinal diseases?

Which one of the following types of waves are used in a Night vision apparatus?

Which one of the following wavelengths corresponds to the wavelength of X-rays?

Which one of the following is not a property of the X-rays?

Which of the following has the longest wavelength?