Question 1

Based on VSEPR theory, what is the molecular shape of hydrogen cyanide (HCN)?

Accepted Answer

Linear

Question 2

Which of the following molecules is non-polar despite having polar bonds?

Accepted Answer

CO$$_2$$

Question 3

Why is the CO$$_2$$ molecule non-polar even though the C=O bonds are polar?

Accepted Answer

The molecule is linear and symmetrical, so the bond dipoles cancel out.

Question 4

Which of the following compounds can form a dative covalent bond with an acid (H$$^+$$)?

Accepted Answer

Water (H$$_2O)$$

Question 5

What is the molecular shape of a water (H$$_2O) $$molecule according to VSEPR theory?

Accepted Answer

Bent (angular)

Question 6

Which of the following molecules exhibits hydrogen bonding between its molecules?

Accepted Answer

NH$$_3$$

Question 7

Why can NH$$_3$$ form a dative covalent bond with BCl$$_3$$?

Accepted Answer

NH$$_3$$ has a lone pair and BCl$$_3$$ has an empty orbital.

Question 8

Which of the following best explains why water (H$$_2O) $$has a higher melting point than carbon tetrachloride (CCl$$_4$$)?

Accepted Answer

Water has stronger hydrogen bonds compared to the London forces in CCl$$_4.$$

Question 9

Which intermolecular force exists in a mixture of H$$_2O $$and CCl$$_4$$?

Accepted Answer

Dipole-induced dipole

Question 10

Consider the OF$$_2$$ molecule. What is its molecular shape and the polarity of its bonds?

Accepted Answer

Bent; weakly polar covalent bonds

Question 11

Which two conditions are required for the formation of a dative covalent bond?

Accepted Answer

One atom must have a lone pair and the other must have an empty orbital.

Question 12

Given the bond energies: CH (413 kJ/mol) and CN (890 kJ/mol), why does the CN bond have a higher bond energy?

Accepted Answer

CN has a higher bond order (triple bond) than CH (single bond).

Question 13

A graph shows the potential energy vs. internuclear distance for a N=N double bond. If the bond energy of a nitrogen triple bond is 946 kJ/mol, how does its bond length compare to the double bond?

Accepted Answer

The triple bond is shorter than the double bond.

Question 14

Which of the following best describes the relationship between bond energy and bond length?

Accepted Answer

The shorter the bond length, the greater the bond energy.

Question 15

Which of the following molecules is polar due to an asymmetrical charge distribution, despite having the same shape as a non-polar molecule?

Accepted Answer

CH$$_3Cl$$

Question 16

Which type of intermolecular force is present in both ammonia (NH$$_3) $$and hypochlorous acid (HOCl)?

Accepted Answer

Hydrogen bonding

Question 17

Why is the HCN molecule polar?

Accepted Answer

Nitrogen is more electronegative than carbon and hydrogen, creating an asymmetrical charge distribution.

Question 18

Which of the following best explains why the bond length of CH is shorter than that of CN, despite CN having a higher bond energy?

Accepted Answer

Hydrogen is much smaller than nitrogen, allowing atoms to get closer together.

Question 19

Which of the following is a real-life application of a dative covalent bond?

Accepted Answer

Formation of the hydronium ion (H$$_3O$^+) in $$water

Atomic Combinations & Molecular Structure: Step-by-Step Chemistry Guidance

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