According to molecular theory, the species among the following that does not exist is:

1.	\(\text {He}_{2}^{+} \)	2.	\(\text {He}_{2}^{-}\)
3.	\(\text {Be}_{2}\)	4.	\(\text O_{2}^{2 -}\)

In $\stackrel{1}{\mathrm{C}}{\mathrm{H}}_2=\stackrel{2}{\mathrm{C}}=\stackrel{3}{\mathrm{C}}\mathrm{H}-\stackrel{4}{\mathrm{C}}{\mathrm{H}}_3$ molecule, the hybridization of carbon 1,2,3 and 4 respectively are :

1. ${\mathrm{sp}}^3,\mathrm{sp},{\mathrm{sp}}^3,{\mathrm{sp}}^3$

2. ${\mathrm{sp}}^2,{\mathrm{sp}}^2,{\mathrm{sp}}^2,{\mathrm{sp}}^3$

3. ${\mathrm{sp}}^2,\mathrm{sp},{\mathrm{sp}}^2,{\mathrm{sp}}^3$

4. ${\mathrm{sp}}^2,{\mathrm{sp}}^3,{\mathrm{sp}}^2,{\mathrm{sp}}^3$

Which pair of oxides are acidic in nature?

1. ${\mathrm{B}}_2{\mathrm{O}}_3,\hspace{0.17em}\mathrm{CaO}$

2. ${\mathrm{B}}_2{\mathrm{O}}_3,\hspace{0.17em}{\mathrm{SiO}}_2$

3. ${\mathrm{N}}_2\mathrm{O},\hspace{0.17em}\mathrm{BaO}$

4. $\mathrm{CaO},\hspace{0.17em}{\mathrm{SiO}}_2$

Match List-I (Molecules) with List-II (Bond order),
and mark the appropriate choice

Choose the correct match from the options given below :

1. (a) $\to$ (iii), (b) $\to$ (iv), (c) $\to$ (i), (d) $\to$ (ii)

2. (a) $\to$ (i), (b) $\to$ (ii), (c) $\to$ (iii), (d) $\to$ (iv)

3. (a) $\to$ (ii), (b) $\to$ (i), (c) $\to$ (iv), (d) $\to$ (iii)

4. (a) $\to$ (iv), (b) $\to$ (iii), (c) $\to$ (ii), (d) $\to$ (i)

In which of the following pairs the two species are not isostructural?

1. PCl₄⁺ and SiCl₄

2. PF₅  and BrF₅

3. AlF₆³⁻ and SF₆

4. CO₃²⁻ and NO₃⁻

Arrange the species \(\mathrm{Li}_2\) , \(\mathrm{Li}_2^{-}\) , and \(\mathrm{Li}_2^{+}\)  in order of increasing stability:

1. ${\mathrm{Li}}_2<{\mathrm{Li}}_2^{-}<{\mathrm{Li}}_2^{+}$

2. \(\mathrm{Li}_2^{-}\) = \(\mathrm{Li}_2^{+}\) = \(\mathrm{Li}_2\)

3. ${\mathrm{Li}}_2<{\mathrm{Li}}_2^{+}<{\mathrm{Li}}_2^{-}$

4. ${\mathrm{Li}}_2^{-}<{\mathrm{Li}}_2^{+}<{\mathrm{Li}}_2$

Which of the following compounds exhibits the highest covalent character?

The ascending order of polarizing power of the following ions is:
\(\mathrm{K}^{+}, \mathrm{Ca}^{2+}, \mathrm{Mg}^{2+}, \mathrm{Be}^{2+}\)

1. Mg²⁺ < Be²⁺ < K⁺ < Ca²⁺

2. Be²⁺ < K⁺ < Ca²⁺ < Mg²⁺

3. K⁺ < Ca²⁺ < Mg²⁺< Be²⁺

4. Ca²⁺ < Mg²⁺ < Be²⁺ < K⁺

How many lone pairs of electrons are present in \({I }_{3}^{-}\) ion?

According to molecular orbital theory, which of the following molecules is not expected to be stable?