AP CHEMISTRY
Week 1 Problem Set
Solution
, AP CHEMISTRY WEEK 1
Problem Set Solution
Problem Set
Multiple Choice Questions
Question 1: What is the electron configuration of Zn2+?
A) Zn2+: 1s2 2s2 2p6 3s2 3p6 4s2 3d8
B) Zn2+: 1s2 2s2 2p6 3s2 3p6 3d10
C) Zn2+: [Ar] 4s2 3d10
D) Zn2+: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2
B, electrons are always removed from the subshell with the highest principle quantum
number
Question 2: A substance has an empirical formula of CH2O and a molar mass of 180.0. What is
its molecular formula?
A) C2H4O2
B) C3H6O3
C) C4H8O4
D) C5H10O5
E) C6H12O6
Calculate the empirical formula mass of CH2O (30g per mole) and divide the molar mass by
it, giving you 180 ÷ 30 = 6. Multiply each of the subscripts in the empirical formula to give
you the molecular formula C6H12O6, answer choice E
Question 3: Why does an ion of phosphorus, P 3− , have a larger radius than a neutral atom of
phosphorus?
A) There is a greater electrostatic attraction between the nucleus and the electrons in P
3−
.
B) The core electrons in P 3− exert a weaker shielding force than those of a neutral atom.
C) The nuclear charge is weaker in P 3− than it is in P.
D) The electrons in P 3− have a greater electrostatic repulsion than those in the neutral
atom.
D The ion has three more electrons than the neutral atom, meaning the overall repulsion
will be greater. The electrons will “push” each other away more effectively, creating a
bigger radius
Question 4: Which of the following is true of the halogens in periods two and three when
comparing them to other elements in the same period?
02
Week 1 Problem Set
Solution
, AP CHEMISTRY WEEK 1
Problem Set Solution
Problem Set
Multiple Choice Questions
Question 1: What is the electron configuration of Zn2+?
A) Zn2+: 1s2 2s2 2p6 3s2 3p6 4s2 3d8
B) Zn2+: 1s2 2s2 2p6 3s2 3p6 3d10
C) Zn2+: [Ar] 4s2 3d10
D) Zn2+: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2
B, electrons are always removed from the subshell with the highest principle quantum
number
Question 2: A substance has an empirical formula of CH2O and a molar mass of 180.0. What is
its molecular formula?
A) C2H4O2
B) C3H6O3
C) C4H8O4
D) C5H10O5
E) C6H12O6
Calculate the empirical formula mass of CH2O (30g per mole) and divide the molar mass by
it, giving you 180 ÷ 30 = 6. Multiply each of the subscripts in the empirical formula to give
you the molecular formula C6H12O6, answer choice E
Question 3: Why does an ion of phosphorus, P 3− , have a larger radius than a neutral atom of
phosphorus?
A) There is a greater electrostatic attraction between the nucleus and the electrons in P
3−
.
B) The core electrons in P 3− exert a weaker shielding force than those of a neutral atom.
C) The nuclear charge is weaker in P 3− than it is in P.
D) The electrons in P 3− have a greater electrostatic repulsion than those in the neutral
atom.
D The ion has three more electrons than the neutral atom, meaning the overall repulsion
will be greater. The electrons will “push” each other away more effectively, creating a
bigger radius
Question 4: Which of the following is true of the halogens in periods two and three when
comparing them to other elements in the same period?
02
