Question

{"given":"Identify the correct statement about subatomic particles and rays from the given options.","key_observation":"Beta rays consist of electrons emitted from the nucleus; cathode rays are also streams of electrons — both consist of the same particle (electron), making option (A) correct.","option_analysis":[{"label":"(A)","text":"Beta rays are the same as cathode rays.","verdict":"correct","explanation":"Both beta rays (emitted during beta decay) and cathode rays are streams of electrons, so they are indeed the same type of particle."},{"label":"(B)","text":"Gamma rays are high-energy neutrons.","verdict":"incorrect","explanation":"Gamma rays are high-energy electromagnetic radiation (photons), not neutrons. They have zero rest mass and travel at the speed of light."},{"label":"(C)","text":"Alpha particles are singly ionized helium atoms.","verdict":"incorrect","explanation":"Alpha particles consist of 2 protons and 2 neutrons, giving them a charge of $+2e$, so they are doubly ionized helium atoms ($\\mathrm{He}^{2+}$), not singly ionized."},{"label":"(D)","text":"Protons and neutrons have exactly the same mass.","verdict":"incorrect","explanation":"The proton mass is approximately $1.6726 \\times 10^{-27}$ kg and the neutron mass is approximately $1.6749 \\times 10^{-27}$ kg — they are nearly but not exactly equal."}],"answer":"(A)","formula_steps":[]}