Chemical Bonding and Molecular Structure Chapter-Wise Test 11

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which molecule has a trigonal pyramidal shape?

In \( \ce{PH3} \), phosphorus is \( sp^3 \) hybridized with one lone pair, leading to a trigonal pyramidal shape with a bond angle less than 109.5°.

\( \ce{BF3} \)
\( \ce{PH3} \)
\( \ce{CO2} \)
\( \ce{BeCl2} \)
2

Which molecule has the shortest bond length among those with a triple bond?

\( \ce{N2} \) has a triple bond with a bond length of ~110 pm, shorter than \( \ce{C2H2} \) (120 pm) or \( \ce{CO} \) (113 pm in MO context) due to high bond order and small atomic size.

\( \ce{C2H2} \)
\( \ce{CO} \)
\( \ce{HCN} \)
\( \ce{N2} \)
4

Which species has a bond order of 2.5?

For \( \ce{O2^+} \): \( (\sigma 1s)^2 (\sigma^* 1s)^2 (\sigma 2s)^2 (\sigma^* 2s)^2 (\sigma 2p_z)^2 (\pi 2p_x)^2 (\pi 2p_y)^2 (\pi^* 2p_x)^1 \). Bonding = 10, antibonding = 5. Bond order = \( \frac{10 - 5}{2} = 2.5 \).

\( \ce{N2} \)
\( \ce{O2} \)
\( \ce{F2} \)
\( \ce{O2^+} \)
4

Which species is diamagnetic and has a bond order of 1?

For \( \ce{H2} \): \( (\sigma 1s)^2 \). Bonding = 2, antibonding = 0. Bond order = \( \frac{2 - 0}{2} = 1 \), with all electrons paired (diamagnetic).

\( \ce{O2} \)
\( \ce{B2} \)
\( \ce{H2} \)
\( \ce{NO} \)
3

The bond formed by the transfer of electrons from a metal to a non-metal is known as:

An ionic bond involves electron transfer, as seen in \( \ce{NaCl} \), where sodium donates an electron to chlorine.

Ionic bond
Covalent bond
Hydrogen bond
Coordinate bond
1

Which molecule does not obey the octet rule due to an expanded octet?

In \( \ce{SF6} \), sulfur has 12 electrons around it, exceeding the octet due to the availability of d orbitals.

\( \ce{NH3} \)
\( \ce{BF3} \)
\( \ce{CH4} \)
\( \ce{SF6} \)
4

In which molecule does the central atom exhibit an incomplete octet?

In \( \ce{BCl3} \), boron has 6 electrons around it (3 bonds), less than an octet, due to having only 3 valence electrons.

\( \ce{NH3} \)
\( \ce{BCl3} \)
\( \ce{PCl5} \)
\( \ce{SF6} \)
2

The number of pi bonds in \( \ce{C4H4} \) (cyclobutadiene) is:

In \( \ce{C4H4} \) (cyclobutadiene, \( \ce{CH=CH-CH=CH} \) in a ring), there are 2 double bonds, each with 1 pi bond, totaling 2 pi bonds, plus 10 sigma bonds.

1
3
4
2
4

The bond angle in \( \ce{ClF3} \) is approximately:

In \( \ce{ClF3} \), chlorine is \( sp^3d \) hybridized with 5 electron pairs (3 bonding, 2 lone), forming a T-shaped molecule with bond angles ~87° due to lone pair repulsion.

109.5°
120°
90°
87°
4

Which molecule has an octahedral electron pair geometry?

In \( \ce{SF6} \), sulfur has six bonding pairs and no lone pairs, with \( sp^3d^2 \) hybridization, giving an octahedral electron pair geometry.

\( \ce{PF5} \)
\( \ce{SF6} \)
\( \ce{XeF4} \)
\( \ce{ClF3} \)
2

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