Chemical Bonding and Molecular Structure Test 31

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Chemical Bonding and Molecular Structure Test 31

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Weekly Quiz Competition

Question 1
1 / -0

Which compound has zero dipole moment?

A

B

C

D

Solution

Only linear groups and atoms, attached at para to each other will have zero dipole moment.

Option C is correct.
Question 2
1 / -0

The number of $$\sigma$$ bonds in o-xylene is

A
$$6$$

B
$$9$$

C
$$12$$

D
$$18$$

Solution

o-xylene has $$18\sigma $$ bonds and $$3\pi$$ bonds.
Question 3
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In which one of the following changes there are transfer of five electrons

A
$$Mn{O}_{4}^{-}\rightarrow {Mn}^{2+}$$

B
$$Cr{O}_{4}^{2-}{Cr}^{3+}$$

C
$$Mn{O}_{4}^{2-}Mn{O}_{2}$$

D
$${Cr}_{2}{O}_{7}^{2-} 2{Cr}^{3+}$$

Solution

$$\overset{+7}{Mn}{O}_{4}^{-}\rightarrow {Mn}^{2+}+5{e}^{-}$$

Option A.
Question 4
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The type of bonding in $$HCl$$ molecule is

A
pure covalent

B
polar covalent

C
highly covalent

D
$$H-$$ bonding

Solution

In $$\mathrm{HCl}$$, Hydrogen atom shares an electron with Chorine atom and the bond is formed. So, the bond is covalent.
But according to Fazan's rule, a covalent bond is always not 100% covalent and an ionic bond is not 100% ionic.

Hence, Option "C" is the correct answer.
Question 5
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Which can be described as a molecule with residual bonding capacity

A
$$BeCl_2$$

B
$$NaCl$$

C
$$CH_4$$

D
$$N_2$$

Solution

Answer is option A $$BeCl_2$$
At room temperature, it exists as a dimer ($$Be_2Cl_4$$), so it has $$\text{residual bonding capacity}$$ because although $$BeCl_2$$ is a complete, neutral molecule, it can form bonds with another molecule to attain further stability.
Question 6
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Peroxide bond is present in

A
$$MgO$$

B
$$CaO$$

C
$$Li_2O$$

D
$$BaO_2$$

Solution

Oxide bond is present in $$MgO$$, $$CaO$$ & $$Li_2O$$, whereas peroxide bond is present in $$BaO_2$$.
Hence, Option "D" is the correct answer.
Question 7
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The enolic form of acetone contains

A
$$8\sigma$$ bonds, $$2\pi-$$ bonds and $$1$$ lone pairs

B
$$9\sigma$$ bonds, $$1\pi-$$ bonds and $$2$$ lone pairs

C
$$9\sigma$$ bonds, $$2\pi-$$ bonds and $$1$$ lone pairs

D
$$10\sigma$$ bonds, $$1\pi-$$ bonds and $$1$$ lone pairs

Solution

It has $$9\sigma$$ bonds, $$1\pi-$$ bond and $$2$$ lone pair (oxygen has two lone pairs).
Question 8
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Acetylene molecules contain

A
$$5\sigma$$ bond

B
$$4\sigma $$ bond and $$1\pi$$ bond

C
$$3\sigma$$ and $$2\pi$$

D
$$3\sigma$$ and $$3\pi$$

Solution

The formula of acetylene is $$C_2H_2\ or \ H-C\equiv C-H$$

$$H\overset{\sigma}{-}C\overset{\sigma}{\equiv }C\overset{\sigma}{-}H$$

$$3\sigma $$ and $$2\pi$$ bonds are present in acetylene.
Question 9
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In $$PO_{4}^{3-}$$ ion the formal charge on the oxygen atom of $$PO$$ bond is

A
$$+1$$

B
$$-1$$

C
$$-0.75$$

D
$$+0.75$$

Solution

The formal charge of an atom in a polyatomic molecule or ion may be defined as the difference between the number of valence electrons of that atom in an isolated or free state and the number of electrons assigned to that atom in the Lewis structure.
$$\text{Formal charge of the atom in the molecule or ion = Number of valence electron in the free atom}$$ $$-$$ $$\text{(Number of lone pair electrons +}$$ $$\dfrac{1}{2}$$ $$\text{number of bonding electrons)}$$
So formal charge on each $$O$$-atom: $$6-(6+\dfrac{1}{2}*2)=6-7=-1$$
Question 10
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$$H_{2}O$$ has a net dipole moment while $$BeF_{2}$$ has zero dipole moment because :

A
F is more electronegative than oxygen

B
Be is more electronegative than oxygen

C
$$H_{2}O$$ molecule is linear and $$BeF_{2}$$ is bent

D
$$BeF_{2}$$ molecule is linear and $$H_{2}O$$ is bent

Solution