In which of the following species central atom is NOT surrounded by exactly 8 valence electrons?

(a) $B{F_4}^{-}$

(b) $NC{l}_3$

(c) PC${l_4}^{+}$

(d) $S{F}_4$

The least polar bond is present in which of the following?

Which set contains only covalently bonded molecules?

(1) $BC{l}_{3 }, SiC{l}_4 ,PC{l}_3$

(2) $N{H}_{4}Br , N_2{H}_4,HBr$

(3) $I_{2 ,}{H}_{2}S , NAI$

(4) $A{l}_2,O_{3 }, A{S}_4$

Which of the following orbital cannot form $\mathrm{\pi }$ as well as $\delta$ bond?

(a)$d_{xy}$       (b) $d_{z^2}$    (c) $d_{x^2-y^2}$   (d) $d_{yz}$

$N{F}_3$ is:

(1) non-polar compound 

(2) electrovalent compound 

(3) having low value of dipole moment than $N{H}_3$

(4) having more dipole moment than $N{H}_3$

The ionisation energy will be maximum for the process:

(a) $Ba\to B{a}^{2+}$

(b) $Be\to B{e}^{2+}$

(c) $Cs\to C{s}^{+}$

(d) $Li\to L{i}^{+}$

Which of the following conversions demonstrates an increase in bond order and a change in magnetic behaviour?

1. $NO\to N{O}^{+}$                                 

2. $O_2\to O_2+$

3. $N_2\to N_2^{+}$                                   

4. $C_2\to C_2^{+}$

The charge/size ratio of a cation determines its polarizing power. Which one of the following sequences represents the increasing order of the polarizing power of the cationic species, 

$K^{+}, C{a}^{+2}, M{g}^{+2}, B{e}^{+2}$

(1) $B{e}^{+2}<K^{+}<C{a}^{+2}<M{g}^{+2}$                     

(2) $K^{+}<C{a}^{+2}<M{g}^{+2}<B{e}^{+2}$

(3) $C{a}^{+2}<M{g}^{+2}<B{e}^{+2}<K^{+}$                     

(4) $M{g}^{+2}<B{e}^{+2}<K^{+}<C{a}^{+2}$

The molecule having the smallest bond angle is-

Which of the following statement is true for $I{O}_2{F_2}^{-}$according to VSEPR theory?

(A) The lone pair and two I-O double bonds occupy the equatorial positions of trigonal
bipyramid.

(B) It has $s{p}^3$ hybridization and is T-shaped.

(C)  Its structure is analogous to $S{F}_4$.

(D) (A) and (C) both