1. Why is the carbon–chlorine bond in chloroalkanes polar?
A.
Carbon and chlorine have different electronegativities
B.
Carbon and chlorine have identical electronegativities
C.
Chlorine has no valence electrons
D.
Carbon is a metal
Correct Answer:
Carbon and chlorine have different electronegativities
Explanation:
The carbon–chlorine bond is polar because chlorine is more electronegative than carbon and attracts the shared electrons more strongly.
2. In a carbon–halogen bond, which atom generally carries a partial negative charge?
A.
The carbon atom
B.
The halogen atom
C.
Both atoms carry a full negative charge
D.
Neither atom carries any charge
Correct Answer:
The halogen atom
Explanation:
The halogen is more electronegative than carbon, so it attracts bonding electrons and acquires a partial negative charge.
3. What is the partial charge on the carbon atom bonded to a halogen in a haloalkane?
A.
Partial positive charge
B.
Partial negative charge
C.
Full positive charge
D.
No charge because the bond is ionic
Correct Answer:
Partial positive charge
Explanation:
The halogen withdraws electron density from carbon, leaving the bonded carbon with a partial positive charge.
4. Which bond in the following compounds is generally polar?
A.
C–C bond in ethane
B.
C–H bond in ethane
C.
C–Cl bond in chloroethane
D.
C–C bond in propane
Correct Answer:
C–Cl bond in chloroethane
Explanation:
The C–Cl bond is polar because chlorine and carbon have a significant difference in electronegativity.
5. The polarity of a carbon–halogen bond mainly results from a difference in:
A.
Atomic mass
B.
Electronegativity
C.
Number of neutrons
D.
Melting point
Correct Answer:
Electronegativity
Explanation:
Bond polarity is caused by unequal sharing of electrons due to a difference in the electronegativities of the bonded atoms.
6. Which symbol correctly represents the charge separation in a C–Cl bond?
A.
Cδ−–Clδ+
B.
Cδ+–Clδ−
C.
C+–Cl− with complete ionic charges
D.
Cδ+–Clδ+
Correct Answer:
Cδ+–Clδ−
Explanation:
Chlorine attracts the bonding electrons more strongly, so carbon becomes partially positive and chlorine becomes partially negative.
7. A polar C–X bond in a haloalkane means that the bonding electrons are:
A.
Shared equally between carbon and halogen
B.
Transferred completely to carbon
C.
Shared unequally between carbon and halogen
D.
Absent from the bond
Correct Answer:
Shared unequally between carbon and halogen
Explanation:
In a polar covalent bond, the electrons are shared unequally because the halogen attracts them more strongly than carbon.
8. Which of the following haloalkanes contains a polar carbon–fluorine bond?
A.
Fluoromethane
B.
Methane
C.
Ethane
D.
Propane
Correct Answer:
Fluoromethane
Explanation:
Fluoromethane contains a C–F bond, and the large electronegativity difference between carbon and fluorine makes this bond polar.
9. What does the presence of a polar C–Br bond indicate in bromoalkanes?
A.
The bonding electrons are attracted more strongly by bromine
B.
The bonding electrons are attracted more strongly by carbon
C.
The bond contains no electrons
D.
The bond is made only of ionic charges
Correct Answer:
The bonding electrons are attracted more strongly by bromine
Explanation:
Bromine is more electronegative than carbon, so it pulls the shared electrons toward itself and makes the C–Br bond polar.
10. Which property is directly associated with polarity in haloalkanes?
A.
Formation of partial positive and partial negative ends
B.
Presence of only neutral atoms with equal electron sharing
C.
Complete loss of all valence electrons
D.
Absence of any carbon–halogen bond
Correct Answer:
Formation of partial positive and partial negative ends
Explanation:
Polarity produces unequal charge distribution, giving the carbon–halogen bond a partial positive end and a partial negative end.
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