Question 1

Which statement best describes the difference between hybrid orbitals and molecular orbitals?

Accepted Answer

Hybrid orbitals result from combinations of orbitals within a given atom, while molecular orbitals result from combinations of orbitals between atoms.

Question 2

What is the ideal bond angle in a molecule where the central atom is $$sp^3$$ hybridized?

Accepted Answer

$$109.5^{\circ}$$

Question 3

Methane ($$CH_4) $$has a tetrahedral geometry. Which orbitals are involved in the bonding of carbon to hydrogen in methane?

Accepted Answer

Four $$sp^3$$ hybrid orbitals from carbon overlap with four $$1s$$ orbitals from hydrogen.

Question 4

Which type of bond is formed by the head-to-head overlap of atomic orbitals?

Accepted Answer

Sigma bond

Question 5

In ethene ($$C_2H_4$$), what is the hybridization of the carbon atoms and the geometry around each carbon?

Accepted Answer

Each carbon is $$sp^2$$ hybridized with trigonal planar geometry.

Question 6

Which of the following statements about pi ($$\pi) $$bonds is TRUE?

Accepted Answer

Pi bonds are formed by sideways overlap of unhybridized $$p$$ orbitals and are generally weaker and more easily broken than sigma bonds.

Question 7

Which of the following molecules contains only sigma ($$\sigma) $$bonds?

Accepted Answer

Methane ($$CH_4)$$

Question 8

What is the general formula for linear alkanes?

Accepted Answer

$$C_nH_{2n+2}$$

Question 9

Which of the following best explains why rotation around a double bond is restricted?

Accepted Answer

The sideways overlap of $$p$$ orbitals in the pi bond prevents free rotation.

Question 10

Which hybridization and bond angle are found in the carbon atoms of acetylene ($$C_2H_2$$)?

Accepted Answer

$$sp$$ hybridization and $$180^{\circ}$$ bond angle

Question 11

Which of the following is a constitutional (structural) isomer of pentane ($$C_5H_{12}$$)?

Accepted Answer

2-methylbutane

Question 12

Which statement about geometric (cis/trans) isomers is correct?

Accepted Answer

They are possible because double bonds restrict rotation, allowing different spatial arrangements of substituents.

Question 13

What is the hybridization of nitrogen in ammonia ($$NH_3$$), and how does it affect the bond angle?

Accepted Answer

Nitrogen is $$sp^3$$ hybridized, but the bond angle is less than $$109.5^{\circ}$$ due to lone pair repulsion.

Question 14

Which of the following statements about the electrons in a pi ($$\pi) $$bond is TRUE?

Accepted Answer

Pi electrons are less tightly bound to the nuclei and can become delocalized under certain conditions.

Question 15

Which of the following best describes the geometry and hybridization of oxygen in water ($$H_2O$$)?

Accepted Answer

Oxygen is $$sp^3$$ hybridized with a distorted tetrahedral geometry due to two lone pairs.

Question 16

Which of the following statements about isomers is correct?

Accepted Answer

Constitutional isomers have different connectivity and different physical and chemical properties.

Question 17

In the molecule $$CH_2$$=$$CHCH_3 ($$propene), what is the hybridization of the central carbon atom?

Accepted Answer

$$sp^2$$

Question 18

Which of the following best explains why pi ($$\pi) $$electrons are more reactive in chemical reactions than sigma ($$\sigma) $$electrons?

Accepted Answer

Pi electrons are more mobile and less localized, making them more available for reaction.

Question 19

Which of the following statements about the hybridization of atoms in a triple bond is correct?

Accepted Answer

Both atoms involved in a triple bond are $$sp$$ hybridized, resulting in linear geometry.

Orbital Hybridization and Molecular Orbitals in Organic Chemistry

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