Bonding in organic molecule - class-XII
bonding in organic molecule
Questions
In which compound enol form is maximum
- $CH _3-\overset{\overset{O}{||}}C-CH _3$
- ${ CH } _{ 3 }-CH=O$
- ${ CH } _{ 3 }-\underset { || }{ C } -{ CH } _{ 2 }-CH _3\\ \quad \quad \quad O$
- ${ CH } _{ 3 }-{ CH _2 } -{ CH } _{ 3 }\\ \quad \quad \quad \quad $
2 mole of ${ H } _{ 3 }{ PO } _{ 4 }$ has:
- Two $\pi $-bond
- Seven mole of $\sigma $-bond
- Sixteen lone pair of electron
- Fourteen mole of $\sigma $-bond
Geometry as sulphur is bent in
I.${S} _{8}$ II.$S{F} _{2}$ III.$S{O} _{2}$
- I, II, III
- I, II
- II, III
- I, III
The enthalpy of reaction,${\text{2HC}} \equiv {\text{CH + 5C}}{{\text{O}} _{\text{2}}}{\text{ + 2}}{{\text{H}} _{\text{2}}}{\text{O}},$
If the bounds energies of ${\text{C - H,C}} \equiv {\text{C,}},{\text{O = O,C = O}}$ abd ${\text{O - H}}$ bounds are p,q,r,s,t respectively
- $\left[ {8s + 4t} \right] - \left[ {4p + q + 5r} \right]$
- $\left[ {4p + 2q + 5r} \right] - \left[ {8s + 4t} \right]$
- $\left[ {4p + 2q + 5r + 8s + 4t} \right]$
- $\left[ {2q + q + 5r + } \right] - \left[ {8s + 4t} \right]$
Decreasing order of bond length of marked carbon oxygen bounds
- $\alpha > \beta >\gamma $
- $\beta >\gamma > \alpha $
- $\beta >\alpha >\gamma $
- $\gamma > \beta > \alpha $
The number of $\displaystyle \sigma-bond$ and $\displaystyle \pi- bond$ in $HCN$ are respectively:
- $2$ and $2$
- $1$ and $3$
- $2$ and $1$
- None of these
Which of the following is not correct?
- A sigma bond is weaker than pi bond.
- A sigma bond is stronger than pi bond.
- A double bond is stronger than a single bond.
- A double bond between two atoms is shorter than a single bond between the same atoms.
Assertion: $\sigma$ is strong while $\pi$ is a weak bond.
Reason : Atoms rotate freely about $\pi$ bond.
- Both assertion and reason are true, and reason is not the true
explanation of the assertion. - Both assertion and reason are true, but reason is the true
explanation of the assertion. - Assertion is true, but reason is false
- Both assertion and reason are false.
The sigma bond energy of $C-H$ bond in $C _{2}H _{6}$ is:
- $99\ kcal$
- $140\ kcal$
- $200\ kcal$
- $60\ kcal$
In carbon-hydrogen-oxygen compounds:
- all $O-$ to $-H$ bonds are $\pi$ bonds
- all $C-$ to $-H$ bonds are $\sigma $ bonds
- all $C-$ to $-C$ bonds are $\sigma $ and/or $\pi$ bonds
- all $C-$ to $-C$ bonds are $\pi$ bonds
$Mg _2C _3$ reacts with water to form propyne. $C _3^{4-}$ has:
- two sigma and two pi bonds
- three sigma and one pi bonds
- two sigma and one pi bonds
- two sigma and three pi bonds
Give the number of $\sigma$ and $\pi$ bonds in (i)$C^{2-} _2$ (ii)$C _3^{4-}$ and (iii)$CN^{2-} _2.$
- (i) 2 $\sigma$, 1 $\pi$; (ii) 1 $\sigma$, 3 $\pi$; (iii) 2 $\sigma$, 2 $\pi$
- (i) 2 $\sigma$, 1 $\pi$; (ii) 3 $\sigma$, 1 $\pi$; (iii) 2 $\sigma$, 2 $\pi$
- (i) 1 $\sigma$, 2 $\pi$; (ii) 2 $\sigma$, 2 $\pi$; (iii) 2 $\sigma$, 2 $\pi$
- (i) 1 $\sigma$, 2 $\pi$; (ii) 3 $\sigma$, 1 $\pi$; (iii) 2 $\sigma$, 2 $\pi$
There is $p\pi\mbox{-}d\pi$ multiple bonding in:
- $CS _2$
- $CO _2$
- $NO _2$
- $NO$
Which of the following compound has a lowest nitrogen-nitrogen bond length?
$N _2, N _2H _2, N _2F _2$.
- $N _2$
- $N _2H _2$
- $ N _2F _2$
- All have equal bond length.
Select the incorrect statement.
- Double bond is shorter than a single bond
- $\sigma$-bond is weaker than a $\pi$-bond
- Double bond is stronger than a single bond
- Covalent bond is stronger than hydrogen bond
Which of the following has $p _{\pi}-d _{\pi}$ bonding?
- $NO _3^-$
- $SO _3^{2-}$
- $BO _3^{3-}$
- $CO _3^{2-}$
Which of the following statement is not correct for sigma and pi-bonds formed between two carbon atoms?
- A sigma bond is stronger than a pi-bond.
- Bond energies of sigma and pi-bonds are of the same order.
- Free rotation of atoms about a sigma bond is allowed but not in case of a pi-bond.
- A sigma bond determines the direction between carbon atoms, but a pi-bond has no primary effect in this regard.
In allene structure, three carbon atoms are joined by :
- three $\sigma$- and three $\pi$-bond
- two $\sigma$- and one $\pi$-bond
- two $\sigma$- and two $\pi$ - bonds
- three $\pi$- bonds only
A triple bond is made of :
- one $\sigma$- and two $\pi$ - bonds
- two $\sigma$- and one $\pi$ - bonds
- three $\sigma$- and three $\pi$ - bonds
- one $\sigma$- and four $\pi$ - bonds
The number of $\sigma$ and $\pi$-bonds in $5$-oxohexanoic acid, respectively, are:
- $18, 2$
- $18, 1$
- $17, 2$
- $17, 1$
Number of $\sigma$ and $\pi$ bonds present in $CH _3-CH=CH- C \equiv CH$ are:
- $10\, \sigma,\, 3\, \pi$
- $10\, \sigma,\, 2\, \pi$
- $9\, \sigma,\, 2\, \pi$
- $8\, \sigma,\, 3\, \pi$
In $N _2$ molecule, the atoms are bonded by:
- $1$ $\sigma$ and $2$ $\pi$ - bonds, $2$ L.P.
- $1$ $\sigma$ and $1$ $\pi$ - bonds, $1$ L.P.
- $2$ $\sigma$ and $1$ $\pi$ - bonds, No L.P.
- $1$ $\sigma$, $2$ $\pi$, and No L.P.
Select the correct statement (s) about the compound $NO[BF _4]$
- It has 5$\sigma$ and 2$\pi$ bond
- Nitrogen - oxygen bond length is higher than nitric oxide $(NO)$
- It is a diamagnetic species
- $BF$ bond length in this compound is lower than in $BF _3$
In the cyclo-$S _8$ molecule of rhombic sulphur, all the $S-S$ bond lengths and all the $S-S-S$ bond angles are respectively (give approximate values):
- $204$ pm and $105^{\circ}$
- $102$ pm and $120^{\circ}$
- $204$ pm and $180^{\circ}$
- $102$ pm and $60^{\circ}$
The triple bond in ethyne is made up of:
- three sigma bonds
- three $\pi$-bonds
- one sigma and two $\pi$-bonds
- two sigma and one $\pi$-bonds
The number of sigma and pi bonds in the structure:
$CH _2, =, CH, -, C, \equiv, CH$
- 7 and 3
- 6 and 2
- 4 and 3
- All are sigma bonds
The number of $\sigma$ bonds and $\pi$-bonds present in $\text{pent-4-en-1-yne}$ is:
- $10,3$
- $4,9$
- $3,10$
- $9,4$
Identify the correct order of bond strengths?
- $\sigma _{p-p}>\pi _{p-p}>\sigma _{s-s}$
- $\sigma _{p-p}>\sigma _{s-s}>\pi _{p-p}$
- $\sigma _{s-s}>\sigma _{p-p}>\pi _{p-p}$
- $\pi _{p-s}>\sigma _{s-s}>\sigma _{p-p}$
In which of the following molecules/ions are all the bonds not equal?
- $BF _4^-$
- $SF _4$
- $SiF _4$
- $XeF _4$
Strength of pi bonds are generally :
- stronger than sigma bond
- weaker than sigma bond
- stronger than ionic bond
- weaker than hydrogen bond
Pent -2-yne has how many $\sigma$ and $\pi$ bonds?
- 10 $\sigma$, 2$\pi$
- 12 $\sigma$, 2$\pi$
- 15 $\sigma$, 2$\pi$
- 13 $\sigma$, 3$\pi$
The correct sequence of bond length in a single bond, a double bond and triple bond of $C$ is:
- ${(C - C) = (C = C) = (C \equiv C)}$
- ${C \equiv C < C = C < C - C}$
- $C - C < C = C < C \equiv C$
- $C = C < C \equiv C < C - C$
$Mg _{2}C _{3}$ reacts with water forming propyne, $C _{2}^{4-}$ has
- Two sigma and two pi bonds
- Three sigma and one pi bonds
- Two sigma and one pi bonds
- Two sigma and three pi bonds
$\displaystyle:Mg _{2}C _{3}$ reacts with water forming propyne, $C _{3}^{4-}$ has:
- two sigma and two pi bonds
- three sigma and one pi bonds
- two sigma and one pi bonds
- two sigma and three pi bonds
Select correct statements about $C^{4-} _3$ ion.
- It reacts with $H _2O$ forming $C _3H _6$.
- It reacts with $H _2O$ forming $C _3H _4$.
- It has two sigma and two pi bonds.
- It has three sigma and one pi bonds.
Which of the following molecule(s) has/have $d _n, -, p _{\pi}$ bonding?
- $H _2S _2O _3$
- $P _4O _{10}$
- $SO _3$
- $P _4S _{10}$
If "$n$" number of $H _3PO _4$ molecules are polymerized to produce chain molecule and ring molecule separately, then the number of $P - O - P$ linkages formed is, respectively :
- $n$ and $(n - 1)$
- $(n - 1)$ and $(n - 1)$
- $(n - 1)$ and $n$
- $n$ and $n$
In $Fe(CO) _5$, the $Fe-C$ bond possesses:
- $\pi$ - character only
- both $\sigma$ and $\pi$ - characters
- ionic character
- $\sigma$ - character only