Arrange the given oxides in decreasing order of their basic character:

1. Na₂O > MgO > Al₂O₃ > CuO

2. MgO > Al₂O₃ > CuO > Na₂O

3. Al₂O₃ > MgO > CuO > Na₂O

4. CuO > Na₂O > MgO > Al₂O₃

Which of the following substances does not exhibit paramagnetism?

1. NO

2. ${\mathrm{N}}_2^{+}$

3. CO

4. ${\mathrm{O}}_2^{-}$

The angular shape of ozone molecule (O₃) consists of 

(a) 1 sigma and 2 pi-bonds

(b) 2 sigma and 2 pi-bonds

(c) 1 sigma and 1 pi-bonds

(d) 2 sigma and 1 pi-bonds

A molecule that has an unequal bond length is : 

According to molecular orbital theory which of the following lists rank the nitrogen species in terms of increasing bond order ?

(1) ${\mathrm{N}}_2^{-} < {\mathrm{N}}_2 < {\mathrm{N}}_2^{2-}$

(2) ${\mathrm{N}}_2^{2-} < {\mathrm{N}}_2^{-} < {\mathrm{N}}_2$

(3) ${\mathrm{N}}_2 < {\mathrm{N}}_2^{2-} <\hspace{0.17em}{\mathrm{N}}_2^{-}$

(4) ${\mathrm{N}}_2^{-} < {\mathrm{N}}_2^{2-} < {\mathrm{N}}_2$

Which one of the following is planar ?

(1) XeF₄

(2) XeO₄

(3) XeO₃

(4) XeO₃F₂

The dielectric constant of H₂O is 80. The electrostatic force of attraction between Na⁺ and Cl^- will be

(1) reduced to $\frac{1}{40}$ in water than in air

(2) reduced to $\frac{1}{80}$ in water than in air

(3) will be increased to 80 in water than in air

(4) will remain unchanged

Which of the following statement is not correct from the view point of molecular orbital theory ?

(1) Be₂ is not a stable molecule

(2) He₂ is not a stable but He_2⁺ is expected to exist.

(3) Bond strength of N₂ is maximum amongst the homonuclear diatomic molecules belonging to the second period.

(4) The order of energies of molecular orbitals in N₂ molecule is

 s2s < s*2s < s2p_z < (p2p_x=p2p_y) < (p*2p_x=p*2p_y) < s*2p_z  

PCl₅ is highly unstable and in solid state it exists as into  [PCl₄]⁺ and [PCl₆]^- ions.

The geometry of [PCl₆]^- is   

(1) octahedral

(2) tetrahedral

(3) square pyramidal

(4) square planar

Which of the following species has maximum number of lone-pair of electrons on the central atom ?

(1) XeF₂

(2) H₃O⁺

(3) XeF₄

(4) XeF₆