What was Democritus's main contribution to atomic theory?(unit 2)

The idea that atoms are indivisible and indestructible

Which is a typical property of an ionic compound?

Conducts electricity when melted

Which part of Dalton’s atomic theory was later proven incorrect?

Atoms of the same element are identical

Which of the following best describes nuclear fusion?

Atoms combine to form a larger nucleus

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

They rearrange to form new substances

Why do scientific models of the atom change over time?

New evidence and technology lead to better understanding

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Chemistry 1 Digital study guide- Enrique Montiel

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Questions 109

Answers

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

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