51.

The bond angle in NF₃ (102.3$°$) is smaller than NH₄ (107.2$°$). This is because of

• large size of F compared to H

• large size of N compared to F

• opposite polarity of N in the two molecules

• small size of H compared to N

The structure of XeF_6, is experimentally determined to be distorted octahedron. Its structure according to VSEPR theory is

• octahedron

• trigonal bipyramid

• pentagonal bipyramid

• tetragonal bipyramid

Addition of excess potassium iodide solution to a solution of mercuric chloride gives the halide complex

• tetrahedral K₂[HgI₄]

• trigonal K [HgI₃]

• linear Hg₂I₂

• square planar K₂[HgCl₂I₂]

Tautomerism is exhibited by

• (Me₃CCO)₃CH

• 

• 

• 

The increasing order of O - N - O bond angle in the species NO₂, NO₂⁺ and NO₂^- is

• NO₂^- < NO₂ < NO₂⁺

• NO₂ < NO₂^- < NO₂⁺

• NO₂⁺ < NO₂^- < NO₂

• NO₂ < NO₂⁺ < NO₂^-

For BCl₃, AlCl₃ and GaCl₃ the increasing order of ionic character is

• BCl₃ < AlCl₃ < GaCl₃

• GaCl₃ < AlCl₃ < BCl₃

• BCl₃ < GaCl₃ < AlCl₃

• AlCl₃ < BCl₃ < GaCl₃

The paramagnetic behaviour of B₂ is due to the presence of

• two unpaired electrons in ${\mathrm{\pi }}_{\mathrm{b}}$ MO

• two unpaired electrons in $\stackrel{*}{\mathrm{\pi }}$ MO

• two unpaired electrons in $\stackrel{*}{\mathrm{\sigma }}$ MO

• two unpaired electrons in ${\mathrm{\sigma }}_{\mathrm{b}}$ MO

CO is practically non-polar since

• the $\mathrm{\sigma }$-electron drift from C to O is almost nullified by the $\mathrm{\pi }$-electron drift from O to C

• the $\mathrm{\sigma }$-electron drift from O to C is almost nullified by the $\mathrm{\pi }$-electron drift from C to O

• the bond moment is low

• there is a triple bond between C and O

The state of hybridization of the central atom and the number of lone pairs over the central atom in POCl₃ are

• sp,0

• sp², 0

• sp³, 0

• dsp², 1

Which one of the following is paramagnetic?

• N₂

• NO

• CO

• O₃