Q: Which of the following best explains why $\mathrm{H_2O}$ is a polar molecule?

The molecule has a bent shape and oxygen is more electronegative than hydrogen.

Q: Which of the following statements about the formation of a covalent bond is correct?

Atoms form covalent bonds to achieve a lower energy state and satisfy the octet rule.

Question 1

Which of the following best describes the energy change when two hydrogen atoms form a covalent bond to make $\mathrm{H_2}$?

Accepted Answer

Energy is released because the system achieves a lower overall energy.

Question 2

Given the bond enthalpies: $\mathrm{H-F}$ (569 kJ/mol), $\mathrm{H-Cl}$ (432 kJ/mol), $\mathrm{H-Br}$ (370 kJ/mol), and $\mathrm{H-I}$ (295 kJ/mol), which bond is the weakest?

Accepted Answer

$\mathrm{H-I}$

Question 3

How many valence electrons does a fluorine atom have?

Accepted Answer

7

Question 4

Which of the following bonds is expected to be the strongest based on bond enthalpy values?

Accepted Answer

$\mathrm{C\equiv C}$

Question 5

A molecule of $\mathrm{CO_2}$ contains which type of bonds between carbon and oxygen?

Accepted Answer

Two double bonds

Question 6

Which of the following best describes the bond in $\mathrm{HF}$?

Accepted Answer

Polar covalent

Question 7

What is the total number of valence electrons in a molecule of $\mathrm{H_2CO}$ (formaldehyde)?

Accepted Answer

12

Question 8

Which of the following statements about bond length and bond strength is correct?

Accepted Answer

Shorter bonds are generally stronger than longer bonds.

Question 9

Which of the following molecules contains a triple bond?

Accepted Answer

$\mathrm{C_2H_2}$

Question 10

Which of the following best explains why $\mathrm{N_2}$ has a much higher bond enthalpy than $\mathrm{O_2}$?

Accepted Answer

$\mathrm{N_2}$ has a triple bond while $\mathrm{O_2}$ has a double bond.

Question 11

Which of the following best describes the bond in $\mathrm{RbBr}$?

Accepted Answer

Ionic

Question 12

A student is drawing the Lewis structure for $\mathrm{CH_3CN}$. What type of bond is present between the carbon and nitrogen atoms?

Accepted Answer

Triple bond

Question 13

Which of the following molecules is expected to have the highest bond polarity?

Accepted Answer

$\mathrm{HF}$

Question 14

What is the maximum number of hydrogen atoms that can be bonded to a hydrocarbon with 6 carbon atoms (an alkane)?

Accepted Answer

14

Question 15

Which of the following best describes the trend in electronegativity across a period in the periodic table?

Accepted Answer

Electronegativity increases from left to right.

Question 16

Which of the following is the correct order of bond strength (from weakest to strongest) for the following carbon-carbon bonds: single, double, triple?

Accepted Answer

Single < Double < Triple

Question 17

A bond between which two elements is most likely to be ionic?

Accepted Answer

Na and Cl

Question 18

Which of the following best explains why $\mathrm{H_2O}$ is a polar molecule?

Accepted Answer

The molecule has a bent shape and oxygen is more electronegative than hydrogen.

Question 19

Which of the following statements about the formation of a covalent bond is correct?

Accepted Answer

Atoms form covalent bonds to achieve a lower energy state and satisfy the octet rule.

Question 20

Which of the following best describes the bond in $\mathrm{BrCl}$?

Accepted Answer

Polar covalent

Covalent Bonding, Bond Strength, and Electronegativity

Study Guide - Practice Questions

Study Guide - Flashcards