The structure of IF₅ can be best described as :

• 

• 

• 

• None of these

From elementary molecular orbital theory we can deduce the electronic configuration of the singly positive nitrogen molecular ion as :

• $\mathrm{\sigma }$1s² , $\stackrel{*}{\mathrm{\sigma }}$1s² , $\mathrm{\sigma }$2s² , $\stackrel{*}{\mathrm{\sigma }}$2s² , $\mathrm{\pi }$2p⁴ , $\mathrm{\sigma }$2p¹

• $\mathrm{\sigma }$1s² , $\stackrel{*}{\mathrm{\sigma }}$1s² , $\mathrm{\sigma }$2s² , $\stackrel{*}{\mathrm{\sigma }}$2s² , $\mathrm{\sigma }$2p² , $\mathrm{\pi }$2p³

• $\mathrm{\sigma }$1s² , $\stackrel{*}{\mathrm{\sigma }}$1s² , $\mathrm{\sigma }$2s² , $\stackrel{*}{\mathrm{\sigma }}$2s² , $\mathrm{\sigma }$2p³ , $\mathrm{\pi }$2p²

• $\mathrm{\sigma }$1s² , $\stackrel{*}{\mathrm{\sigma }}$1s² , $\mathrm{\sigma }$2s² , $\stackrel{*}{\mathrm{\sigma }}$2s² , $\mathrm{\sigma }$2p² , $\mathrm{\pi }$2p⁴

Which of the following has largest atomic radii ?

• Al

• Al⁺

• Al²⁺

• Al³⁺

Ionisation potential is lowest for :

• alkali metals

• inert gases

• halogens

• alkaline earth metals

The percentage of p-character in the orbitals forming P-P bond in P₄ is :

• 25

• 33

• 50

• 75

6.

The valence shell electronic configuration of Cr²⁺ ion is :

• 4s⁰3d⁴

• 3p⁶4s²

• 4s³3d²

• 4s²3d⁰

A solution contains 25% H₂O , 25% C₂H₅OH and 50% CH₃COOH by mass .The mole fraction of H₂O would be :

• 0.25

• 2.5

• 0.502

• 5.03

If the solubility of PbCl₂ at 25°C is 6.3 x 10^-2 mol/L , its solubility product is :

• 1 x 10^-6

• 1 x 10^-3

• 1.1 x 10^-6

• 1.1 x 10^-5

A double bond connecting two atoms .There is a sharing of :

• 2 electrons

• 1 electron

• 4 electrons

• All electrons

pH of a solution can be expressed as :

• -log_e [H⁺]

• -log₁₀ [H⁺]

• log_e [H⁺]

• log₁₀[H⁺]