Final answer:
Among the options, Kr, representing krypton, is the noble gas. Noble gases are found in the right-most column of the periodic table.
Step-by-step explanation:
The question asks which of the given elements is a noble gas. Noble gases are a group of chemical elements with similar properties on the rightmost column of the periodic table. These gases are helium, neon, argon, krypton, xenon, and radon. In relation to your options, the correct answer is (d) Kr, which represents krypton. Krypton is indeed a noble gas, while rb (rubidium), mn (manganese), and cl (chlorine) are not.
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