AnswersIASD Chemistry Q2 2025-2026 HuntsmanUnit Test

Unit Test — Unit test Answers

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1
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Which statement best describes how electrons fill orbitals in the periodic table?

A
Electrons fill orbitals in order of their increasing energy from left to right.
B
Electrons fill orbitals in order of their increasing energy from right to left.
C
Elements fill orbitals in order of increasing energy from top to bottom in each group.
D
Elements fill orbitals in order of increasing energy from bottom to top in each group.
2
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In which orbitals would the valence electrons for selenium (Se) be placed?

A
s orbital and f orbital
B
s orbital only
C
s orbital and p orbital
D
d orbital only
3

What is the atomic number of zirconium?

A
39
B
40
C
41
D
42
4

Which element is the most reactive?

A
sodium
B
nickel
C
carbon
D
oxygen
5

Among the elements of the main group, the general trend in the first ionization energy moving across a period is not followed between group 2 and group 13. Which best explains these exceptions?

A
The ionization energy decreases because the full s orbital shields the electron entering the p orbital.
B
The ionization energy increases because the full s orbital shields the electron entering the p orbital.
C
The ionization energy decreases because the stability of the half-full p subshell is increased.
D
The ionization energy increases because the stability of the half-full p subshell is increased.
6

Which best explains why ionization energy tends to decrease from the top to the bottom of a group?

A
The number of orbitals decreases.
B
The number of neutrons decreases.
C
Electrons get closer to the nucleus.
D
Electrons get farther from the nucleus.
7

Which element has the largest atomic radius?

A
As
B
N
C
P
D
Sb
8

When electrons are removed from the outermost shell of a calcium atom, the atom becomes

A
an anion that has a larger radius than the atom.
B
an anion that has a smaller radius than the atom.
C
a cation that has a larger radius than the atom.
D
a cation that has a smaller radius than the atom.
9

How many valence electrons does aluminum (Al) have available for bonding?

A
1
B
2
C
3
D
4
10

Which of the following symbols would be included in the noble gas notation for an element that had valence electrons in the 5s subshell?

A
Ar
B
Kr
C
Xe
D
Rn
11

The elements of which group are nonreactive?

A
halogens
B
alkaline earth metals
C
noble gases
D
alkali metals
12

Which element is classified as an alkali metal?

A
Rb
B
Sr
C
Zr
D
Cl
13

Moseley made revisions to the periodic table that resolved some of the problems with Mendeleev’s version. Which of these was a result of his revisions to the periodic table?

A
The revised periodic table could account for the discovery of new elements.
B
The revised periodic table could account for variations resulting from isotopes.
C
Scientists could begin to write new information onto each element.
D
Scientists could begin to place the table on a single sheet of paper.
14

How did the work of Dmitri Mendeleev differ from that of John Newlands in the development of the periodic table?

A
Mendeleev arranged the elements according to increasing atomic mass.
B
Mendeleev predicted elements that would later be discovered.
C
Mendeleev identified elements that had similar properties.
D
Mendeleev organized elements into triads based on their properties.
15

How did Moseley establish a more accurate periodic table?

A
by arranging the elements according to atomic mass instead of atomic number
B
by arranging the elements according to atomic number instead of atomic mass
C
by arranging the elements into horizontal periods
D
by arranging the elements into vertical groups
16

Which explains the change in ionization energy that occurs between removing the first and second electrons from an atom?

A
The ionization energy decreases because the ratio of the protons to electrons increases.
B
The ionization energy increases because the ratio of the protons to electrons increases.
C
The ionization energy decreases because the ratio of the protons to electrons decreases.
D
The ionization energy increases because the ratio of the protons to electrons decreases.
17

In which block of the periodic table is chromium (Cr) found?

A
s block
B
d block
C
p block
D
f block
18

Selected properties of antimony (Sb) and iodine (I) are listed in the table below.ElementAtomic radius(pm)First ionization energy(kJ/mol)Electron affinity(kJ/mol)ElectronegativitySb145?–1032.05I1401008–295?Which predictions can most likely be made?

A
Sb has a lower ionization energy but a higher electronegativity than I.
B
Sb has a higher ionization energy but a lower electronegativity than I.
C
Sb has a lower ionization energy and a lower electronegativity than I.
D
Sb has a higher ionization energy and a higher electronegativity than I.
19

Which is the electronic configuration for oxygen?

A
1s2 2s2 2p1
B
1s2 2s2 2p3
C
1s2 2s2 2p4
D
1s2 2s2 2p6
20

Members of which group easily lose an electron to form a +1 cation?

A
halogens
B
alkaline earth metals
C
noble gases
D
alkali metals

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