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

The number of sigma bonds in P₄O₁₀ is 

(1) 6

(2) 16

(3) 20

(4) 7

A s bonded molecule MX₃ is T-shaped. The number of non-bonding pairs of electrons is :

(1) 0

(2) 2

(3) 1

(4) Can be predicted only if atomic number of M is known,

In a chemical change from ${\mathrm{PCl}}_3 \stackrel{ }{\to }{\mathrm{PCl}}_5$ the hybrid state of P changes from:

(1) sp² to sp³

(2) sp³ to sp²

(3) sp³ to sp³d

(4) sp³ to dsp

In which case observed dipole moment is greater than theoretical dipole moment?

1.

2.

3.

4.

Amongst ${\mathrm{H}}_2\mathrm{O}, {\mathrm{H}}_2\mathrm{S}, {\mathrm{H}}_2\mathrm{Se} \mathrm{and} {\mathrm{H}}_2\mathrm{Te}$ the one with the highest boiling point is:

1. H₂O because of H-bonding.

2. H₂Te because of higher molecular weight.

3. H₂S because of H-bonding.

4. H₂Se because of lower molecular weight.

Which of the following species contains an equal number of $\mathrm{\sigma }$ and $\mathrm{\pi }$ bonds?

(a) ${\mathrm{HCO}}_3^{-}$                                    (b) XeO₄

(c) (CN)₂                                      (d) CH₂(CN)₂

Which one of he following pairs is isostructural (i.e., having the same shape and hybridization)?
(a) [BCl₃ and BrCl₃]

(b) [NH₃ and ${\mathrm{NO}}_3^{-}$]

(c) [NF₃ and BF₃]

(d) [${\mathrm{BF}}_4^{-}$ and ${\mathrm{NH}}_4^{+}$]