Half-life is the time it takes for...

Half of a radioactive sample to decay

Which of the following best describes nuclear fusion?

Atoms combine to form a larger nucleus

What happens to atoms during a chemical reaction?(unit 7)

They rearrange to form new substances

According to the Kinetic Molecular Theory, which is not true of ideal gas particles?

They have significant attractive forces

Why are elements placed in the same group (vertical column) on the periodic table? (unit 3)

They have the same number of valence electrons

According to Collision Theory, what must happen for a reaction to occur?(unit 11)

Reactants must collide with sufficient energy and proper orientation

What did Niels Bohr propose in his atomic model?

Electrons orbit the nucleus in fixed energy levels

Which describes theoretical yield?

The amount predicted by stoichiometry

Which of the following is true about Lewis structures?

The total number of electrons must match the valence electrons

Why do scientific models of the atom change over time?

New evidence and technology lead to better understanding

Which calculation shows how to find the average atomic mass?

Multiply each isotope's mass by its abundance and add the results

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Chemistry 1 Digital study guide- Enrique Montiel

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Questions 109

Answers

1
Given 18g of H₂O, how many grams of H₂ are formed in 2H₂ + O₂ → 2H₂O?
1.0 g
8.0 g
2.0 g
4.0 g
2
Which group contains elements that are highly reactive and form +1 ions?
Noble gases
Transition metals
Alkali metals
Halogens
3
What is the molar mass of water (H₂O)?
18.0 g/mol
20.0 g/mol
16.0 g/mol
10.0 g/mol
4
Half-life is the time it takes for...
A sample to lose all its electrons
Half of a radioactive sample to decay
All of a sample to decay
A sample to double
5
Which of the following best describes nuclear fusion?
Atoms combine to form a larger nucleus
Large nucleus splits
Electrons are emitted
Neutrons are captured
6
which of the following is NOT a correct lab safety rule?(unit 1)
Never leave a flame unattended
Taste chemicals
Always wear googles when handling chemicals
Notify your teacher for spills
7
If heat is released and ΔH is negative, the process is:
Neutral
Isothermal
Endothermic
Exothermic
8
Which particles are found in the nucleus of an atom?
neutrons and electrons
electrons and protons
only protons
protons and neutrons
9
Electrons are located in...
Neutron shells
Electron clouds/orbitals
The nucleus
Fixed orbits
10
What happens to atoms during a chemical reaction?(unit 7)
They split into quarks
They rearrange to form new substances
They disappear and reform
They remain unchanged in arrangement
11
Which element has the orbital diagram: ↑↓ ↑↓ ↑↓ ↑↓ ↑_ ↑_?
Fluorine
Nitrogen
Oxygen
Carbon
12
Which factor causes a molecule to be polar?
High melting point
Lone pairs on the central atom
Identical surrounding atoms
Symmetrical electron distribution
13
What is emitted in the following decay: ²¹⁴₈₄Po → ²¹⁰₈₂Pb + ?
Alpha particle
Neutron
Beta particle
Gamma ray
14
What is the charge on a calcium ion (Ca)?
+1
+2
-1
-2
15
Which of the following has the largest atomic radius?
Lithium
Fluorine
Potassium
Neon
16
How many grams of NaCl are needed to make 2.0 L of 1.0 M solution? (NaCl = 58.5 g/mol)
29.3 g
117 g
58.5 g
2.0 g
17
Which is the balanced form of the reaction: _C₃H₈ + _O₂ → _CO₂ + H₂O?
1, 3, 3, 4
1, 4, 4, 3
1, 4, 3, 3
1, 5, 3, 4
18
According to the Kinetic Molecular Theory, which is not true of ideal gas particles?
They occupy negligible volume
They undergo elastic collisions
They have significant attractive forces
They move in constant, straight-line motion
19
What is the full electron configuration of magnesium (Mg)?
1s² 2s² 2p⁶
1s² 2s² 2p⁶ 3s¹
1s² 2s² 2p⁶ 3p²
1s² 2s² 2p⁶ 3s²
20
Which of the following is not a typical indicator of a chemical reaction?
Gas production
Dissolving salt in water
Color change
Change in temperature
21
Why are elements placed in the same group (vertical column) on the periodic table? (unit 3)
They have the same number of neutrons
They have the same mass number
They have the same number of valence electrons
They have the same atomic number
22
What is the temperature in Kelvin if the Celsius temperature is 25°C?
248 K
298 K
225 K
273 K
23
Which of the following has the highest boiling point due to intermolecular forces?
CH₄
CO₂
O₂
NH₃
24
According to Collision Theory, what must happen for a reaction to occur?(unit 11)
Atoms must be the same size
Reactants must collide with sufficient energy and proper orientation
Reactants must dissolve
Reactants must cool down
25
If you have 10g of H₂ and 80g of O₂, which is the limiting reactant in forming water?
H₂
O₂
H₂O
Neither
26
Which prefix represents 1/100 of a unit?
milli
micro
kilo
centi
27
What is the name of the constant 6.022 × 10²³?
Rutherford’s number
. Dalton’s constant
Bohr’s constant
Avogadro’s number
28
How many valence electrons are in a molecule of CH₄?
6
8
14
10
29
Which is the correct skeleton equation for: “Hydrogen reacts with oxygen to form water”?
H + O₂ → H₂O
H₂ + O₂ → H₂O
H₂ + O → H₂O
H₂O → H₂ + O₂
30
What did Niels Bohr propose in his atomic model?
Electrons orbit the nucleus in fixed energy levels
Electrons are embedded in a positively charged sphere
Electrons move randomly around the nucleus
The atom has no internal structure
31
In the reaction NH₃ + H₂O ⇌ NH₄⁺ + OH⁻, what is the conjugate acid?
H₂O
OH⁻
NH₄⁺
NH₃
32
Which is the correct unit for molar mass?
g/mol
g
amu
mo
33
Which of the following is not one of the diatomic elements?
Chlorine
Carbon
Nitrogen
Fluorine
34
How many valence electrons does phosphorus (P) have?
3
5
13
15
35
Which is the correct way to write an isotope of Carbon with 6 protons and 8 neutrons?
C-8
¹⁴₆C
⁶₁₄C
¹²C
36
Which describes theoretical yield?
The mass of the limiting reactant
The amount left over after a reaction
The amount produced in the lab
The amount predicted by stoichiometry
37
What is the pH of a solution with [H⁺] = 1.0 × 10⁻⁴ M?
10
6
2
4
38
Which discovery is Thomson known for?
The electron
The neutron
Energy levels
The nucleus
39
A solution with a pH of 3 is:
Slightly acidic
Slightly basic
Strongly acidic
Neutral
40
If a 100g sample decays to 25g in 6 hours, what is the half-life?
2 hours
1.5 hours
6 hours
3 hours
41
Which of the following is true about Lewis structures?
The central atom always gets all lone pairs
The total number of electrons must match the valence electrons
Only bonding electrons are shown
Lone pairs are not important
42
Which type of bond forms between a metal and a nonmetal?(unit 5)
hydrogen
covalent
metallic
ionic
43
Which of the following is a diatomic element?
Aluminum
Oxygen
Sulfur
Neon
44
How is the modern periodic table organized?
By increasing atomic number
By increasing mass number
By decreasing reactivity
By increasing number of neutrons
45
Why do scientific models of the atom change over time?
Atoms behave differently in experiments
Older models are always wrong
New evidence and technology lead to better understanding
Scientists guess different structures
46
What are the units for the mass of a single atom?
g
g/mol
amu
mol
47
What is the charge and symbol for an electron?
0, n
-1, e⁻
+1, p
+1, e⁺
48
What are the products of the reaction: HCl + NaOH → ?
H₂ + NaCl
H₂O + NaCl
Cl₂ + NaOH
H₂O + Na
49
Which calculation shows how to find the average atomic mass?
Multiply each isotope's mass by its abundance and add the results
Divide mass number by atomic number
Add the mass numbers of all isotopes
Multiply atomic number by abundance
50
When an electron absorbs energy, it...
Moves to a lower energy level
Moves to a higher energy level
Becomes a proton
Leaves the atom
51
Which formula represents the ideal gas law?
P₁V₁ = P₂V
V/T = k
P₁/T₁ = P₂/T₂
PV = nRT
52
According to Bronsted-Lowry theory, an acid is a:
Electron donor
OH⁻ donor
Proton donor
Proton acceptor
53
In a metallic bond, how do the electrons behave?
Transferred from one atom to another
Shared between two specific atoms
Free to move in a "sea of electrons"
Repelled to the outer energy level
54
What is the molarity of a solution with 2 moles of solute in 1 liter of solution?
1 M
0.5 M
1 M
3 M
55
What is the correct formula for magnesium chloride?
MgCl
Mg₂Cl₃
Mg₂Cl
MgCl₂
56
What does the atomic number represent?
Protons + Neutrons
Mass of the atom
Number of neutrons
Number of protons
57
What is the formula for sulfuric acid?
H₂SO₄
H₂S
H₂SO₃
HSO₄
58
Which of the following is a strong acid?
H₂CO₃
HCl
CH₃COOH
NH₃
59
Which VSEPR shape describes a molecule with 4 bonding pairs and no lone pairs?
Linear
Trigonal planar
Tetrahedral
Bent
60
Valence electrons are found...
In the innermost shell
Only in metals
In the nucleus
In the outermost shell
61
What did Rutherford’s gold foil experiment reveal about the atom?
Electrons orbit in energy levels
Atoms contain a dense nucleus and are mostly empty space
Atoms are solid throughout
Atoms emit radiation
62
A student gets five very similar results that are far from the accepted value. This shows:
High precision, low accuracy
High accuracy and precision
Low accuracy and precision
High accuracy, low precision
63
What are the products of the combustion of methane (CH₄)?
H₂ and CO₂
CH₃OH
C and H₂
CO₂ and H₂O
64
Which is a typical property of an ionic compound?
Conducts electricity when melted
Low melting point
Made of only nonmetals
Soft and flexible
65
When reading a graduated cylinder, what should you do?
Ignore the decimal places
Record the number at the top of the meniscus
Round to the nearest whole number
Estimate between the smallest marks
66
Which compound demonstrates an octet exception for boron?
H₂O
CH₄
BH₃
CO₂
67
Which is the strongest type of intermolecular force?
Hydrogen bonding
Dipole-dipole
Metallic bonding
London dispersion
68
If you have 2 moles of N₂, how many moles of NH₃ can be produced?
6
3
4
2
69
Which of the following best defines a mole in chemistry?(unit 4)
The atomic number of an element
The number of protons in an atom
6.022 × 10²³ particles of a substance
The mass of one atom in grams
70
Which of the following correctly ranks the bond lengths from longest to shortest?(unit 6)
Triple > Single > Double
Single = Triple > Double
Single > Double > Triple
Double > Single > Triple
71
How many neutrons are in an atom with mass number 23 and atomic number 11?
23
11
34
12
72
Breaking bonds is always:
A physical change
Spontaneous
Exothermic
Endothermic
73
What percent of water's mass is oxygen (H₂O)?
89%
33%
66%
11%
74
How many atoms are in Ca(OH)₂?
6
4
3
5
75
What is the most common charge of zinc (Zn)?
+3
+2
+4
+1
76
What was Democritus's main contribution to atomic theory?(unit 2)
Electrons orbit the nucleus in energy levels
Discovery of the nucleus
The idea that atoms are indivisible and indestructible
Atoms contain neutrons in the nucleus
77
On an energy diagram, what does the peak represent?
Products
Activation energy
ΔH
Reactants
78
Which radiation has the highest penetrating power?
neutron
alpha
beta
gamma
79
What is the modern atomic model that describes regions where electrons are likely to be found?
Plum Pudding Model
Bohr Model
Solid Sphere Model
Quantum Mechanical Model
80
Which element has the highest electronegativity?
Sodium
Helium
Fluorine
Oxygen
81
Which type of reaction is represented by: 2Na + Cl₂ → 2NaCl
Single replacement
Decomposition
Synthesis
Double replacement
82
What is the correct name for CO₂?
Dicarbon monoxide
Carbon dioxide
Carbon oxide
Carbon monoxide
83
If your theoretical yield is 15g and your actual yield is 12g, what is your percent yield?
95%
85%
80%
90%
84
Based on its position, which element is most likely to be a poor conductor and brittle?
Iron
Sodium
Copper
Phosphorus
85
Which orbital has a spherical shape?
s
p
d
f
86
Which of the following molecules is polar?
CCl₄
CH₄
CO₂
NH₃
87
Which of the following is true for an isotope?
Different number of protons
Different atomic number
Different number of electrons
Different number of neutrons
88
A catalyst increases reaction rate by:
Decreasing activation energy
ncreasing temperature
Creating more reactants
Increasing product mass
89
If the measured mass of a sample is 9.5 g and the accepted value is 10.0 g, what is the percent error?
95%
5%
50%
0.5%
90
Which of the following describes an exothermic reaction?
Energy is absorbed
Temperature decreases
Products have less energy than reactants
ΔH is positive
91
If a molecule has 2 bonding pairs and 2 lone pairs, what is the molecular shape?
Bent
Linear
Trigonal planar
Tetrahedral
92
What is the purpose of titration?
To form a solid
To determine concentration of an unknown solution
To find molar mass
To measure temperature
93
What is the molar mass of O₂?
8.00 g/mol
32.00 g/mol
16.00 g/mol
64.00 g/mol
94
What is the formula for sulfate?
SO₃²⁻
S₂O₃²
SO₄²⁻
SO₂
95
As the temperature of a gas increases, what happens to the kinetic energy of the particles?
It decreases
It increases
It becomes zero
It stays the same
96
Which factor does not affect reaction rate?
Surface area
Color of the reactants
Temperature
Presence of a catalyst
97
Convert 1250 milliliters (mL) to liters (L):
125,000 L
1.25 L
0.125 L
12.5 L
98
In the equation: N₂ + 3H₂ → 2NH₃, what is the mole ratio of H₂ to NH₃?(unit8)
2:3
3:2
2:1
1:3
99
Which of the following is a chemical bond, not an intermolecular force?
Hydrogen bond
Covalent bond
London dispersion force
Dipole-dipole interaction
100
Which subatomic particle has the smallest mass?
neutron
electron
proton
all are equal
101
What is the sum of pH and pOH in any aqueous solution at 25°C?
10
14
0
7
102
If the average atomic mass of chlorine is 35.45, which isotope is more abundant?
Cl-37
Cl-35
All equally
Cl-36
103
If volume decreases and temperature is constant, what happens to pressure?
Increases
Decreases
Stays the same
Cannot be predicted
104
What is the molar mass of sodium (Na)?
11.00 g/mol
22.99 g/mol
22.99 g
22.99 amu
105
In saltwater, what is the solute?(unit 10)
both
nither
salt
water
106
Which part of Dalton’s atomic theory was later proven incorrect?
Atoms are indivisible by chemical processes
Atoms are solid spheres
Atoms of the same element are identical
Atoms combine in whole number ratios
107
How many atoms are in 2.00 mol of carbon?
3.01 × 10²³
6.02 × 10²³
1.20 × 10²⁴
2.00 × 10²²
108
An electron is in the ground state when...
It is moving between levels
It is ionized
It is at its lowest energy level
It is outside the atom
109
Which statement is true about accuracy and precision?
Accuracy is reproducibility; precision is closeness to the true value
They are the same in scientific measurement
Both refer to how close values are to each other
Precision is reproducibility; accuracy is closeness to the true value

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