The electronic configuration of three elements $A, B$ and $C$ are given below. The molecular formula of the compound formed from $B$ and $C$ will be
$A : 1s^2, 2s^2, 2p^6$
$B : 1s^2, 2s^2, 2p^6, 3s^2, 3p^3$
$C : 1s^2, 2s^2, 2p^6, 3s^2, 3p^5$

Among the following,the least and most metallic elements will be respectively:
$(I) [He] 2s^1$
$(II) [Kr] 5s^2 4d^{10} 5p^5$
$(III) [Xe] 6s^1$
$(IV) [He] 2s^2 2p^5$

Which elements are classified as metalloids? Name them.

Metallic nature and basic nature of the oxides $........$ as we move along a period.

Statement $I :$ Acid strength increases in the order given as $HF < HCl < HBr < HI$.
Statement $II :$ As the size of the elements $F, Cl, Br, I$ increases down the group,the bond strength of $HF, HCl, HBr$ and $HI$ decreases and so the acid strength increases.
In the light of the above statements,choose the correct answer from the options given below.

If $M^{+3}$ has configuration $[Ar]3d^{10}$,then $M$ belongs to :-