Which of the following is the most basic oxide?
(1) Al₂O₃

(2) Sb₂O₃

(3) Bi₂O₃

(4) SeO₂

Which of the following is not a correct statement?

(1) The electron-deficient molecules can act as Lewis acids

(2) The canonical structures have no real existence

(3) Every AB₅ molecule does, in fact, have square pyramid structure

(4) Multiple bonds are always shorter than corresponding single bonds

The number of unpaired electrons in a paramagnetic diatomic molecule of an element with atomic mass 16 is :

1. 2

2. 3

3. 4

4. 1

Which of the following is not isostructural with SiCl₄?

(a) SCl₄            (b) ${\mathrm{SO}}_4^{2-}$               (c) ${\mathrm{PO}}_4^{3-}$                 (d) ${\mathrm{NH}}_4^{+}$

Least stable hydride is:

(1) stannane 

(2) silane 

(3)  plumbane 

(4) germane

Correct order of strength of H-bond in the following compounds is : 

(1) $H_{2}O > H_2{O}_2 > HF > H_{2}S$ 

(2) $HF \ge H_2{O}_2 > H_{2}O > H_{2}S$

(3) $HF >\hspace{0.17em}{H}_{2}O > H_{2}S > H_2{O}_2$

(4) $HF >\hspace{0.17em}{H}_2{O}_2 > H_{2}O > H_{2}S$

Molecule having non-polar as well as polar bonds but the molecule as a whole is polar:

(a) $S_2{F}_2$

(b) ${\mathrm{N}}_2{\mathrm{O}}_4$

(c) ${\mathrm{Si}}_2{\mathrm{H}}_6$                                           

(d) ${\mathrm{I}}_2{\mathrm{Cl}}_6$

Choose the correct statement regarding $SeOC{l}_2$ molecule:

1. It does not contain a plane of symmetry

2. $\text{'}\mathrm{Cl}-\widehat{\mathrm{Se}}-\mathrm{Cl}\text{'} \mathrm{bond} \mathrm{is} \mathrm{greater} \mathrm{than} \text{'}\mathrm{Cl}-\widehat{\mathrm{Se}}-\mathrm{O}\text{'} \mathrm{bond} \mathrm{angle}$

3. Lone pair has greater than 33.3% s-character

4.  Central atom used one d-orbital in bonding.

Which of the following compounds can form H-bonding with each other? 

(a) $C{H}_3 COOH and H_{2}O$

(b) Phenol and $C{H}_4$

(c) $CH{F}_3 and acetone$

(d) $P{H}_{3 }and HF$

Which of the following compound is planar and non-polar?

(1) $Xe O_4$

(2) $S{f}_4$

(3) $Xe f_4$

(4) $C{f}_4$