121.

The number of sigma (σ) and pi ($\mathrm{\pi }$) bonds present in 1, 3, 5, 7-octatetraene respectively are

• 14 and 3

• 17 and 4

• 16 and 5

• 15 and 4

The molecule that contains only sp² hybrid carbon atoms is

• isoprene

• acrylonitrile

• but-1-ene

• 1,3-butadiene

Among the following, the molecule of highest dipole moment is

• CCl₄

• NH₃

• H₂O

• CHCl₃

The incorrectly matched pair, among the following is-

• BrF₅ - Trigonal bipyramidal

• SF₄ - See-saw

• ClF₃ - T-shape

• NH₃ - Trigonal pyramidal

Which one of the following has the shortest bond length?

• C - H

• C - N

• C - F

• C - C

Pick out the wrong statement.

• Nitrogen has the ability to form p$\mathrm{\pi }$-p$\mathrm{\pi }$ bonds with itself

• Bismuth forms metallic bonds in elemental state

• Catenation tendency is higher in nitrogen when compared with other elements of the same group

• Nitrogen has higher first ionization enthalpy when compared with other elements of the same group

The wrong statement about the interstitial compounds is

• their melting points are lower than those of pure metals

• they retain metallic conductivity

• they are chemically inert

• their bonds are neither ionic non covalent

Which of the following is not correct with respect to bond length of the species? 

• C₂ > ${\mathrm{C}}_2^{2-}$

• ${\mathrm{B}}_2^{+}$ > B₂

• ${\mathrm{Li}}_2^{+}$ > Li₂

• O₂ > O${}_2^{-}$

Substance which is weakly repelled by a magnetic field is

• O₂

• H₂O

• CrO₂

• Fe₃O₄

The bonds present in the structure of dichromate ion are

• four equivalent Cr-O bonds only

• six equivalent Cr-O bonds and one Cr - O - O bond

• six equivalent Cr-O bonds and one O-O bond

• eight equivalent Cr-O bonds