alleryWhich of the following inert (noble) gases is placed in period 4 of the periodic table?
ARn
BXe
CAr
DKr
Answer & Solution
Correct answer: D. Kr
1. Noble gases occupy group 18; each period ends with one.
2. Period 3 ends with Ar, period 4 with Kr, period 5 with Xe, period 6 with Rn.
3. So the period-4 noble gas is Krypton (Kr).
_Source: RRB Group D CEN-02/2018 PYQ, Q.50._
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