Q: A photon has a wavelength of $4.00 \times 10^{-7}\ \mathrm{m}$. What is its frequency ($\nu$)? (Speed of light $c = 3.00 \times 10^8\ \mathrm{m/s}$)

$\nu = 7.50 \times 10^{14}\ \mathrm{Hz}$

Question 1

Which of the following statements best describes the Law of Conservation of Energy as it applies to a chemical reaction occurring in a closed system?

Accepted Answer

The total energy of the system and surroundings remains constant; energy can be converted from one form to another but cannot be created or destroyed.

Question 2

A sample of water is heated from 25 $^\circ$C to 75 $^\circ$C. If the mass of water is 100 g and the specific heat capacity of water is $4.18\ \mathrm{J/(g \cdot ^\circ C)}$, how much heat ($q$) is absorbed by the water?

Accepted Answer

$q = 20,900\ \mathrm{J}$

Question 3

Which of the following best describes the difference between kinetic and potential energy in the context of a chemical reaction?

Accepted Answer

Kinetic energy is the energy of motion of particles, while potential energy is stored in chemical bonds.

Question 4

A reaction has an enthalpy change $\Delta H = -125\ \mathrm{kJ}$. Which of the following statements is true?

Accepted Answer

The reaction is exothermic and releases heat to the surroundings.

Question 5

Given the balanced equation: $2\ \mathrm{H}_2(g) + \mathrm{O}_2(g) \rightarrow 2\ \mathrm{H}_2\mathrm{O}(l)$, and $\Delta H = -571.6\ \mathrm{kJ}$, what is the enthalpy change for the formation of 1 mole of $\mathrm{H}_2\mathrm{O}(l)$?

Accepted Answer

$\Delta H = -285.8\ \mathrm{kJ}$

Question 6

Which of the following correctly expresses the relationship between wavelength ($\lambda$), frequency ($
u$), and the speed of light ($c$)?

Accepted Answer

$c = \lambda 
u$

Question 7

A photon has a wavelength of $4.00 	imes 10^{-7}\ \mathrm{m}$. What is its frequency ($
u$)? (Speed of light $c = 3.00 	imes 10^8\ \mathrm{m/s}$)

Accepted Answer

$
u = 7.50 	imes 10^{14}\ \mathrm{Hz}$

Question 8

Which of the following is a correct application of Heisenberg's uncertainty principle?

Accepted Answer

It is impossible to simultaneously know both the exact position and exact momentum of an electron.

Question 9

How many electrons can be held in all the $p$ orbitals of a single energy level?

Accepted Answer

6

Question 10

Which set of quantum numbers is NOT allowed for an electron in an atom?

Accepted Answer

$n=2,\ l=2,\ m_l=0,\ m_s=+\frac{1}{2}$

Question 11

Which of the following elements has the largest atomic radius?

Accepted Answer

Potassium ($\mathrm{K}$)

Question 12

Which of the following ions has the smallest ionic radius?

Accepted Answer

$\mathrm{Al}^{3+}$

Question 13

Which of the following statements about ionization energy is correct?

Accepted Answer

Ionization energy generally increases across a period from left to right.

Question 14

Which of the following molecules is nonpolar, despite having polar bonds?

Accepted Answer

$\mathrm{CO}_2$

Question 15

Which of the following best describes the bonding in sodium chloride ($\mathrm{NaCl}$)?

Accepted Answer

Ionic bonding, due to the transfer of electrons from sodium to chlorine.

Question 16

Which of the following is the correct Lewis structure for the carbonate ion ($\mathrm{CO}_3^{2-}$)?

Accepted Answer

Three resonance structures, each with one double bond between carbon and one oxygen, and two single bonds to the other oxygens, with a -1 formal charge on each singly bonded oxygen.

Question 17

Which of the following molecules has a trigonal planar electron geometry according to VSEPR theory?

Accepted Answer

$\mathrm{BF}_3$

Question 18

Which of the following statements about sigma ($\sigma$) and pi ($\pi$) bonds is correct?

Accepted Answer

A double bond consists of one $\sigma$ bond and one $\pi$ bond.

Question 19

Which of the following best explains why $\mathrm{H}_2\mathrm{O}$ is a polar molecule?

Accepted Answer

It has polar O-H bonds and a bent molecular geometry, resulting in a net dipole moment.

Question 20

Which of the following is an exception to the octet rule?

Accepted Answer

$\mathrm{BF}_3$

General Chemistry Study Guide: Energy, Quantum Mechanics, Periodic Table, and Chemical Bonding

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