Which of the following instruments is used in detecting the presence of radiation?

The instrument used in detecting the presence of radiation is the Geiger-Muller counter. Radiation refers to the emission of energy in the form of particles or waves. This can include gamma rays, beta particles, and alpha particles, among others. The Geiger-Muller counter is a device that is used to detect and measure ionizing radiation, such as alpha and beta particles, gamma rays, and X-rays. The Geiger-Muller counter works by using a gas-filled tube that contains a wire electrode. When ionizing radiation enters the tube, it ionizes the gas atoms, which then cause a cascade of electrons to move toward the wire electrode. This generates a pulse of electrical current that is detected and counted by the device. The number of pulses detected per unit time is proportional to the intensity of the radiation present. Out of the given options, the only instrument used in detecting the presence of radiation is the Geiger-Muller counter. - Cathode ray tube: This instrument is used to generate and manipulate a focused beam of electrons in a vacuum. It is commonly used in televisions and computer monitors. - Mass spectrometer: This instrument is used to determine the mass of individual atoms and molecules in a sample by ionizing them and separating them based on their mass-to-charge ratio. It is commonly used in chemistry and physics research. - X-ray tube: This instrument is used to generate X-rays by accelerating electrons and colliding them with a metal target. X-rays are commonly used in medical imaging. Therefore, the correct answer is the Geiger-Muller counter.