4. Chemical bonding and molecular structure — Chemistry STD 11 Science — Question

$(A)$ All are isoelectronic

$(B)$ All have the same nuclear charge

$(C)$ $\mathrm{O}^{2-}$ has the largest ionic radii

$(D)$ $\mathrm{Mg}^{2+}$ has the smallest ionic radii

Choose the most appropriate answer from the options given below :

$B\xleftarrow{{Pd + CaC{O_3}}}R - C \equiv C - R\xrightarrow{{liq.N{H_3} + Na}}A$

$A$ and $B$ are geometrical Isomers. Then