Which of the following molecules has the maximum dipole moment ?
A
CO2
B
CH4
C
NH3
D
NF3
Explanation
Even though for CO2 and CH4 the C - O and
C - H bonds are polar but due to their symmetrical
structure they have zero dipole moment.
In NH3, H is less electronegative than N and hence the dipole moment of each N-H bond
is towards N which is in the similar direction of lone pair but for NF3
the dipole moment of N-F bond is in opposite
direction of lone pair which reduce the value of
net dipole moment.
2
NEET 2013
MCQ (Single Correct Answer)
Identify the correct order of solubility in aqueous medium.
A
Na2S > CuS > ZnS
B
Na2S > ZnS > CuS
C
Cus > ZnS > Na2S
D
ZnS > Na2S > CuS
Explanation
Water is a polar compound so the salt which
is more polar or having more ionic character will
be more soluble in it. According to Fajan's rule,
ionic character of compound increases with
increase in the size of cation. Now, among the given
compounds, the size of cations are in the order as
follows :
Na+ > Zn2+ > Cu2+
Thus, the order of ionic character and the solubility
order in aqueous medium is as follows :
Na2S > ZnS > CuS
3
NEET 2013 (Karnataka)
MCQ (Single Correct Answer)
In which of the following ionization processes the bond energy increases and the magnetic behaviour changes from paramagnetic to diamagnetic.
The outer orbitals of C in ethane molecule can be considered to be hybridized to give three equivalent sp2 orbitals. The total number of sigma $$\left( \sigma \right)$$ and pi $$\left( \pi \right)$$ bonds in ethane molecule is
A
3 sigma $$\left( \sigma \right)$$ and 2 pi $$\left( \pi \right)$$ bonds
B
4 sigma $$\left( \sigma \right)$$ and 1 pi $$\left( \pi \right)$$ bonds
C
5 sigma $$\left( \sigma \right)$$ and 1 pi $$\left( \pi \right)$$ bonds
D
1 sigma $$\left( \sigma \right)$$ and 2 pi $$\left( \pi \right)$$ bonds
Explanation
Questions Asked from Chemical Bonding and Molecular Structure
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