Tag: tetravalence of carbon: shapes of organic compounds

Questions Related to tetravalence of carbon: shapes of organic compounds

Number of $\sigma$ and $\pi$ bonds present in $CH _3-CH=CH- C \equiv CH$ are:

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. $10\, \sigma,\, 3\, \pi$

  2. $10\, \sigma,\, 2\, \pi$

  3. $9\, \sigma,\, 2\, \pi$

  4. $8\, \sigma,\, 3\, \pi$

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Correct Option: A
Explanation:

Sigma bonds are formed by axial overlap and pi bonds are formed by sideways overlap. total number of bonds are $10\, \sigma,\, 3\, \pi$.

In $N _2$ molecule, the atoms are bonded by:

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. $1$ $\sigma$ and $2$ $\pi$ - bonds, $2$ L.P.

  2. $1$ $\sigma$ and $1$ $\pi$ - bonds, $1$ L.P.

  3. $2$ $\sigma$ and $1$ $\pi$ - bonds, No L.P.

  4. $1$ $\sigma$, $2$ $\pi$, and No L.P.

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Correct Option: A
Explanation:
${ N } _{ 2 }$ molecule contains $2$ lone pairs and $1s$ and $2p$ bonds.
$:N\equiv N:$
A triple bond consist of $1$ sigma and two $pi$ bonds. Lone pair refers to a pair of valence electrons that are not shared with another atom, it is also called non-bonding pair.

Select the correct statement (s) about the compound $NO[BF _4]$

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. It has 5$\sigma$ and 2$\pi$ bond

  2. Nitrogen - oxygen bond length is higher than nitric oxide $(NO)$

  3. It is a diamagnetic species

  4. $BF$ bond length in this compound is lower than in $BF _3$

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Correct Option: A,C
Explanation:

$NO[BF _4]$ can be separated into $NO^+$ and $BF _4^-$. 
$BF _4^-$ has $4$  bonds, as single bonds between $B$ and $F$.
$NO^+$ has $1$  bonds, $2$ bonds.
It is a diamagnetic species.

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): 

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. $204$ pm and $105^{\circ}$

  2. $102$ pm and $120^{\circ}$

  3. $204$ pm and $180^{\circ}$

  4. $102$ pm and $60^{\circ}$

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Correct Option: A
Explanation:

There is a single bond between each pair of $S$ atoms and two non-bonding electron pairs on each $S$ atom.Thus we see four electron domains around each $S$ atom and we would expect a tetrahedral geometry corresponding to $sp^3$ hybridisation which gives us the bond angle around $109^0$.

The triple bond in ethyne is made up of:

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. three sigma bonds

  2. three $\pi$-bonds

  3. one sigma and two $\pi$-bonds

  4. two sigma and one $\pi$-bonds

Show answer
Correct Option: C
Explanation:

In case of any multiple bonds, one bond is always sigma. In ethyne, rest $2$ are pi bonds.

The number of sigma and pi bonds in the structure:
$CH _2\, =\, CH\, -\, C\, \equiv\, CH$

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. 7 and 3

  2. 6 and 2

  3. 4 and 3

  4. All are sigma bonds

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Correct Option: A
Explanation:

In $H _{2}C = CH-C\equiv CH$, there are $4: C-H$ sigma bonds and $3: C-C$ sigma bonds, thus it has a total of $7 \sigma$ bonds. Also there are $3 \pi$ bonds in the structure.

The number of $\sigma$ bonds and $\pi$-bonds present in $\text{pent-4-en-1-yne}$ is:

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. $10,3$

  2. $4,9$

  3. $3,10$

  4. $9,4$

Show answer
Correct Option: A
Explanation:

$HC\equiv C-{CH} _{2}-CH={CH} _{2}$


$\text{Pent-4-en-1-yne}$

Triple bond between $C$ and $C$ contains one $\sigma$ bond and two $\pi$ bonds. Double bond between $C$ and $C$ contains one $\sigma$ bond and one $\pi$ bond.

Total $\sigma$ bonds$=10$

Total $\pi$ bonds $=3$

Hence, the correct option is $\text{A}$

Identify the correct order of bond strengths?

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. $\sigma _{p-p}>\pi _{p-p}>\sigma _{s-s}$

  2. $\sigma _{p-p}>\sigma _{s-s}>\pi _{p-p}$

  3. $\sigma _{s-s}>\sigma _{p-p}>\pi _{p-p}$

  4. $\pi _{p-s}>\sigma _{s-s}>\sigma _{p-p}$

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Correct Option: C
Explanation:

The correct order of bond strengths is $\displaystyle \sigma _{s-s}>\sigma _{p-p}>\pi _{p-p}$
The extent of overlap is higher for s orbital than for  p orbital. Higher is the extent of overlap, stronger is the bond formed.
Also, $\displaystyle \sigma$ bond is stronger than $\displaystyle \pi$ bond.

In which of the following molecules/ions are all the bonds not equal?

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. $BF _4^-$

  2. $SF _4$

  3. $SiF _4$

  4. $XeF _4$

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Correct Option: B

Strength of pi bonds are generally :

chemistry introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

  1. stronger than sigma bond

  2. weaker than sigma bond

  3. stronger than ionic bond

  4. weaker than hydrogen bond

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Correct Option: B
Explanation:

Strength of pi bond is weaker than sigma bond because it is formed due to lateral overlapping of atomic orbitals. 
Since, their is a sharing of electron between the two atoms, which is not in case of hydrogen bond, hence it is stronger than the hydrogen bond.
Ionic bonds are always stronger than the covalent bonds. Since, Pi bonds are covalent bonds hence, it is weaker than ionic bonds.