CHEM 121 UPDATED ACTUAL EXAM QUESTIONS CORRECT ANSWERS GRADED A PLUS FORM TWO

CHEM 121 UPDATED ACTUAL EXAM QUESTIONS CORRECT ANSWERS GRADED A PLUS
FORM TWO
CHEM 121 Final Question and Answe5 Questions
and Answers Verified Solutions Latest Update
2026/2027

Question:
Which of the following atomic species has only two unpaired electrons?

Answer:
S



Question:
Which neutral atom has the electron configuration [Kr]5s24d105p6?

Answer:
Xe



Question:
A common frequency used to transmit cellular data by one of the major United States telecoms
providers is 1900 MHz. What is the wavelength in centimeters of these radio waves?

Answer:
15.8 cm



Question:
Which set of the following quantum numbers represent an electron in the p subshell?

Answer:
n = 2, l = 1, ms = 0, ms = +1/2



Question:

,A photon of light from a laser has an energy of 2.287 × 10-19 J. What is the total energy in two
moles of these photos?

Answer:
274.4 kJ



Question:
Using the Bohr model, determine the energy of an electron with n = 5 in a helium atom.

Answer:
-3.486 × 10-19 J



Question:
A local radio station broadcasts music at a frequency of 9.33 x 107 s-1 (93.3 MHz). What is the
wavelength of these radio waves in meters?

Answer:
3.21 m



Question:
Calculate the energy in joules of an electron in a hydrogen atom transitioning from the n = 3 to the n
= 4 energy level.

Answer:
1.069 × 10-19 J



Question:
Nitrous oxide, N2O, commonly known as laughing gas, is used as an anesthetic in minor surgeries,
such as the routine extraction of wisdom teeth. Which is the correct statement regarding the number
of bonds and lone pairs? (Note: the atomic sequence is NNO)

Answer:
one single bond, one triple bond, and four lone pairs.

,Question:
Rank the following ions in order of decreasing atomic radii: Mo4+, Mo5+, Mo6+.

Answer:
Mo6+ > Mo5+ > Mo4+



Question:
Atoms of an element X have the ground-state electron configuration 1s22s22p63s23p4. What type
of ion is X most likely to form?

Answer:
X2-



Question:
Which of the following compounds has a Lewis structure that does NOT break the octet rule?

Answer:
CO2



Question:
Which of the following atoms is the least electronegative?

Answer:
Fr



Question:
After drawing the Lewis structure for phosphine (PH3), how many single bonds, double bonds and
lone pairs are on the phosphorous atom?

Answer:
three single bonds, no double bonds, and 1 lone pair.

, Question:
Of all the noble gases, xenon is the most reactive, frequently reacting with elements such as oxygen
and fluorine. Predict the electron-pair geometry of the XeF4 molecule.

Answer:
Octahedral



Question:
Which of the following species does not have a ground-state noble-gas electron configuration?

Answer:
F



Question:
Evaluate the following statements and determine which statement(s) concerning electronegativity
is/are incorrect? 1. Differences in element electronegativities may be used to predict the type of
bonding, ionic or covalent, in a substance. 2. The larger the differences in electronegativity between
two bonded atoms the more polar the bond. 3. The electrons in a polar bond tend to spend more time
around the least electronegative element.

Answer:
3 only



Question:
The most stable Lewis structure for the nitrite ion has how many total single bonds, double bonds
and lone pairs?

Answer:
one single bond, one double bond, and six lone pairs.



Question:
Which of the following species is isoelectronic with Kr?