A) \[Li\]
B) \[Ce\]
C) \[Na\]
D) \[Ra\]
Correct Answer: D
Solution :
Elements with atomic number greater than 82 are naturally radioactive (a)\[Li\,\,at.\,\,no.=3\] (b)\[Ce\,\,at.\,\,no.=58\] (c)\[Na\,\,at.\,\,no.=11\] (d)\[Ra\,\,at.\,\,no.=88\] \[\therefore \,\,\,Ra\]is radioactiveYou need to login to perform this action.
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