Multiple Choice QuestionsThe percentage of p-character of the hybrid orbitals in graphite and diamond are respectively
50 and 75
67 and 75
33 and 75
33 and 25
An alkali metal hydride (NaH) reacts with diborane in. A to give a tetrahedral compound B which is extensively used as reducing agent in organic synthesis. The compounds A and B respectively are
C2H6 and C2H5Na
CH3COCH3 and B3N3H6
C6H6 and NaBH4
(C2H5)2O and NaBH4
The correct statement is
BF3 is the strongest Lewis acid among the other boron halides
BI3 is the weakest Lewis acid among the other boron halides
there is maximum pπ- pπ back boinding in BF3
there is minimum pπ- pπ back boinding in BF3
The hybridisation of C in diamond, graphite and ethyne is in the order.
sp3, sp, sp2
sp3, sp2, sp
sp, sp2, sp3
sp2, sp3, sp
B.
sp3, sp2, sp
(i) As diamond has tetrahedral structure in which all the C-atoms are bonded by4 σ-bonds with 4 neighbouring C-atoms. Thus, it has sp3 hybridisation.
(ii) Graphite forms an hexagonal sheet like structure in which each C-atom is bonded by 3 σ-bonds with 3-C atoms in the same plane, 4th electron of C-atom is free to move thus, show sp2 hybridisation.
(iii) Ethyne has CH≡CH structure, in which one C-atom is bonded with other C-atom through only one σ-bond (as -bonds do not take part in hybridisation). Thus, it shows sp-hybridisation.
Hence, correct order is : sp3, sp2, sp.
The electronegativities of C, N, Si and P are in the order of
P < Si<C < N
Si <P < C<N
P < Si < N < C
Si <P < N <C
Addition of mineral acid to an aqueous solution of borax, the following compound is formed
pyroboric acid
boron hydride
meta boric acid
orthoboric acid
Which of the following equations correctly represents the standard heat of formation (H) of methane ?
C (diamond) + 4H (g) → CH4 (g)
C (diamond) + 2H2 (g) → CH4 (g)
C (graphite) + 2H2 (g) → CH4 (g)
C (graphite) + 4H (g) → CH4 (g)
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