Chemical Bonding and Molecular State NDA Questions

NDA Chemistry

Chemical Bonding and Molecular State MCQ Questions


7.
In BF3, the boron atom has only six electrons around it in the Lewis structure; this is an example of a molecule with:
A.
A perfect octet
B.
A hypervalent structure
C.
An incomplete octet
D.
An expanded octet
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ANSWER :
C. An incomplete octet
8.
Molecules like NO and NO2, which contain an unpaired electron, are examples of:
A.
Purely ionic molecules
B.
Molecules with expanded octets
C.
Odd-electron molecules
D.
Molecules obeying the duplet rule
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ANSWER :
C. Odd-electron molecules
9.
A Lewis dot symbol for an atom is used to represent its:
A.
Valence electrons
B.
Atomic mass
C.
Neutrons
D.
Total electrons
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ANSWER :
A. Valence electrons
10.
The number of dots surrounding the symbol of nitrogen (atomic number 7) in its Lewis dot structure is:
A.
3
B.
7
C.
4
D.
5
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ANSWER :
D. 5
11.
The formal charge on an atom equals its valence electrons minus non-bonding electrons minus:
A.
Half of the bonding (shared) electrons
B.
The number of lone pairs only
C.
Twice the bonding electrons
D.
All of the bonding electrons
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ANSWER :
A. Half of the bonding (shared) electrons
12.
In the Lewis structure O=C=O for carbon dioxide, the formal charge on the carbon atom is:
A.
−1
B.
0
C.
+1
D.
+2
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ANSWER :
B. 0