Chemistry Practice Midterm Part 2
This quiz is to help prepare first year chemistry students for their first semester exam.
- 1.
What is the difference between an element and a compound?
- A.
An element is a homogeneous mixture and a compound is a heterogeneous mixture.
- B.
An element is a pure substance and a compound is a physical mixture of elements.
- C.
An element is a pure substance and a compound is a chemical combination of elements.
- D.
None of these are correct.
Correct Answer
C. An element is a pure substance and a compound is a chemical combination of elements.Explanation
Elements are the simplest form of a pure substance and a compound is the chemical combination of these. Both are considered pure substances and not mixtures.Rate this question:
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- 2.
You have 5.5 grams of Hydrogen in 50. grams of water. What is the percent of oxygen by mass?
- A.
11%
- B.
9.0%
- C.
.89 %
- D.
89 %
Correct Answer
D. 89 %Explanation
Percent by Mass = (mass of element)/(mass of compound) x 100%. In this case, 50 grams of water - 5.5 grams of hydrogen = 44.5 grams of oxygen. (44.5 g /50. g) x 100% = 89%Rate this question:
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- 3.
Which Law best describes this statement:"Mass is not created or destroyed, only rearranged."
- A.
Law of Conservation of Mass
- B.
Law of Definite Proportions
- C.
Law of Multiple Proportions
- D.
Law of Octaves
Correct Answer
A. Law of Conservation of MassExplanation
Law of Conservation of Mass states that matter is neither created nor destroyed and is conserved in a chemical reaction.Rate this question:
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- 4.
If I mix 8.8 grams of hydrogen with oxygen and get 80. grams of water, how many grams of oxygen did I use?
- A.
9. g
- B.
80. g
- C.
71. g
- D.
You need more information to answer this question.
Correct Answer
C. 71. gExplanation
The Law of Conservation of Mass states that the total mass of the reactants (hydrogen gas and oxygen gas) must equal the total mass of the products. 80 g - 8.8 g = 71.2 g. With sig figs, 71.2 g is reduced to 71. g.Rate this question:
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- 5.
What does the 6 in the above symbol represent?
- A.
Mass number
- B.
Atomic number
- C.
Atomic mass
- D.
None of these
Correct Answer
B. Atomic numberExplanation
Atomic number is always the smallest whole number in the symbol and represents the number of protons.Rate this question:
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- 6.
What does 12.011 in the above symbol represent?
- A.
Mass number
- B.
Atomic number
- C.
Atomic mass
- D.
None of these.
Correct Answer
C. Atomic massExplanation
Mass number is the number of protons + neutrons and is a whole number. Atomic mass is not a whole number because it is an average of naturally occurring isotopes.Rate this question:
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- 7.
Which of the following are true about isotopes?
- A.
The number of protons are the same, but the number of neutrons are different.
- B.
The number of protons are the same, but the number of electrons are different.
- C.
The number of neutrons are the same, but the number of electrons are different.
- D.
Two of these are correct.
Correct Answer
A. The number of protons are the same, but the number of neutrons are different.Explanation
Isotopes have the same number of protons but different number of neutrons and therefore have a different mass number.Rate this question:
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- 8.
What is the definition of frequency?
- A.
The energy of a wave.
- B.
How fast the wave is going.
- C.
One full cycle of a wave pattern.
- D.
The number of waves that pass a particular point in a second.
Correct Answer
D. The number of waves that pass a particular point in a second.Explanation
Speed is how fast the wave is going and wavelength is a full cycle of a wave pattern (crest to crest or trough to trough).Rate this question:
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- 9.
How many valence electrons does Sulfur have?
- A.
2
- B.
4
- C.
6
- D.
8
Correct Answer
C. 6Explanation
You can determine the number of valence electrons an atom has by looking at its group number. Sulfur is in group 16 and therefore has 6 valence electrons.Rate this question:
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- 10.
Use the following equations and Plank's constant (6.626 x 10-34 Js) to find the amount of energy carried by a photon that has a frequency of 5.00 x 1014 Hz.c= (wavelength) vE = hv
- A.
7.55 x 10^-21 J
- B.
9.06 x 10^26 J
- C.
3.31 x 10^-19 J
- D.
6.00 x 10^-7 J
Correct Answer
C. 3.31 x 10^-19 JExplanation
Use E=hv to find energy. Multiply Planck's constant by the given frequency.Rate this question:
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- 11.
Use the following equations and Plank's constant (6.626 x 10-34 Js) to find the frequency of light that has a wavelength of 440. nmc= (wavelength) vE = hv
- A.
6.82 x 10^14 Hz
- B.
6.82 x 10^16 Hz
- C.
4.52 x 10^-19 Hz
- D.
2.92 x 10^42 Hz
Correct Answer
A. 6.82 x 10^14 HzExplanation
Use c= (wavelength) v. Convert your wavelength of 440. nm to 4.40 x 10^-7 m. Divide the speed of light (3.00 x 10^8 m/s) by the wavelength.Rate this question:
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- 12.
Use the following equations and Plank's constant (6.626 x 10-34 Js) to find the wavelength of a photon that has the energy of 5.00 x 10-19 J?c= (wavelength) vE = hv
- A.
7.55 x 10^14 nm
- B.
3.98 x 10^-7 nm
- C.
398 nm
- D.
600. nm
Correct Answer
C. 398 nmExplanation
You need to use both equations. Start with the E=hv and solve for v (frequency). Use frequency (7.55 x 10^14 Hz) in c = (wavelength)v to solve for wavelength. Answer will be in meters. Convert 3.98 x 10^-7 to nm.Rate this question:
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- 13.
What type of elements are brittle solids?
- A.
Metals
- B.
Nonmetals
- C.
Metalloids
- D.
Transition metals
Correct Answer
B. NonmetalsExplanation
Metals are shiny, conductive, malleable and ductile. Nonmetals are gases, liquids or dull, brittle solids. Metalloids share these characteristics.Rate this question:
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- 14.
Where is the f block located on the periodic table.
- A.
The block to the far left.
- B.
The block in the middle.
- C.
The block to the far right.
- D.
The block below the main table.
Correct Answer
D. The block below the main table.Explanation
S block is to the left, d block in the middle, p block to the right and f block below.Rate this question:
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- 15.
What is the name of group 2?
- A.
Alkali metals
- B.
Alkaline earth metals
- C.
Halogens
- D.
Noble gases.
Correct Answer
B. Alkaline earth metalsExplanation
Group 1=alkali metals, Group 2= alkaline earth metals, Group 17= halogens, Group 18= noble gases.Rate this question:
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- 16.
What is the periodic trend for electronegativity?
- A.
Increases going left to right and increases going down.
- B.
Increases going left to right and decreases going down.
- C.
Decreases going left to right and increases going down.
- D.
Decreases going left to right and decreases going down.
Correct Answer
B. Increases going left to right and decreases going down.Explanation
Electronegativity is the measure of the attraction of electrons. Fluorine is the most electronegative element because it has only 7 valence electrons and a low number of energy levels. The periodic trend for electronegativity will increase towards fluorine.Rate this question:
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- 17.
What is the periodic trend for ionization energy?
- A.
Increases going left to right and increases going down.
- B.
Increases going left to right and decreases going down.
- C.
Decreases going left to right and increases going down.
- D.
Decreases going left to right and decreases going down.
Correct Answer
B. Increases going left to right and decreases going down.Explanation
The periodic trend for ionization energy is the same as electronegativity. It increases as you move across left to right because the energy to remove a valence electron will increase as the elements acquire more electrons. The trend decreases going down the periodic table because as energy levels are added to the atom, the nucleus has a lesser hold on the valence electrons.Rate this question:
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- 18.
What is ionization energy?
- A.
Electron love.
- B.
The energy that it takes to gain an electron.
- C.
The energy that it takes to remove an electron.
- D.
Energy associated with losing 3 valence electrons
Correct Answer
C. The energy that it takes to remove an electron.Explanation
Ionization energy is the energy required to remove an electron from an atom or ion. It is a measure of the strength of the attraction between the electron and the nucleus of the atom. The higher the ionization energy, the more difficult it is to remove an electron. Therefore, the correct answer is "The energy that it takes to remove an electron."Rate this question:
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- 19.
Which of the following is the largest in terms of radius?
- A.
Br-
- B.
Br
- C.
Cl
- D.
F
Correct Answer
A. Br-Explanation
Negative ions are larger than neutral atoms due to the electromagnetic repulsion of the valence electrons. Also, the trend in atomic radius increases as it moves down the periodic table due to the added layers of energy levels.Rate this question:
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- 20.
What element has the electron configuration of:[Ar] 4s2 3d5
- A.
Mn
- B.
Tc
- C.
Br
- D.
Cl
Correct Answer
A. MnExplanation
The highest energy level listed is 4; therefore the element has to be in the 4th row on the periodic table. 3d5 tells us that it has 5 electrons in the 3rd d energy level (which is in the 4th row).Rate this question:
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- 21.
Which block on the period table has can hold 14 electrons
- A.
S
- B.
P
- C.
D
- D.
F
Correct Answer
D. FExplanation
The f sublevel has 7 orbitals and can hold a total of 14 electrons. 2 electrons per orbital.Rate this question:
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- 22.
Where are the metals located on the periodic table.
- A.
S block
- B.
D and f block
- C.
Left of the 'staircase'
- D.
More than one of these is correct.
Correct Answer
D. More than one of these is correct.Explanation
Metals are located to the left of the staircase, which includes the s,d and f blocks. The p block is split between metals and nonmetals at the staircase.Rate this question:
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- 23.
Which of the following are not one of the main parts of the scientific method?
- A.
Hypothesis
- B.
Observation
- C.
Experiment
- D.
All these are correct.
Correct Answer
D. All these are correct.Explanation
Observation, hypothesis, experiment and conclusion are all a part of the scientific method. You should know what they mean for the exam.Rate this question:
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- 24.
If I have a 1.0 liter jar in which I keep my lost marbles. What would be the mass of the marbles in the jar if each marble takes up approximately 1.3 ml of space and has a mass of 3.5 g. Assume that the marbles use the space efficiently.
- A.
27 kg
- B.
0.27 kg
- C.
2.7 kg
- D.
It is impossible to figure out since the jar is 3 dimensional.
Correct Answer
C. 2.7 kgExplanation
1.0 liter = 1000ml. (1000ml/1) x (1 marble/1.3ml) = 769 marbles. (769 marbles/1) x (3.5 grams/1 marble) = 2692 grams. 2692 grams = 2.7 kg.Rate this question:
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- 25.
Convert 820 nm to meters.
- A.
8.2 x 10^-9 m
- B.
8.2 x 10^7 m
- C.
8.2 x 10^9 m
- D.
8.2 x 10^-7 m
Correct Answer
D. 8.2 x 10^-7 mExplanation
nm = 1 x 10^-9.Rate this question:
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- 26.
What is the average atomic mass for copper if Cu-63 is 65.0% abundant and Cu-65 is 35.0% abundant?
- A.
63.0 amu
- B.
63.7 amu
- C.
64.0 amu
- D.
63.5 amu
Correct Answer
B. 63.7 amuExplanation
Cu-63 and Cu-65 are isotopes. 63 and 65 are mass numbers. (65% of 63) + (35% of 65) = 63.7 amuRate this question:
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- 27.
What did Dalton get right with his Atomic Theory?
- A.
That atoms are not divisible.
- B.
That atoms are identical in size and mass.
- C.
The Law of Conservation of Mass.
- D.
Atoms of the same element have isotopes.
Correct Answer
C. The Law of Conservation of Mass.Explanation
Dalton stated that matter was rearranged in chemical reactions but not destroyed or created. This is the basis of the Law of Conservation of Mass. You should know about Dalton's Atomic Theory for the test.Rate this question:
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- 28.
Which of these are not an example of the dual nature of light?
- A.
Wavelength
- B.
Photoelectric effect.
- C.
Color
- D.
Frequency
- E.
All of the above are considered a part of the dual nature of light.
Correct Answer
E. All of the above are considered a part of the dual nature of light.Explanation
The dual nature of light is the particle and wave nature that light. All characteristics of waves are considered examples. Wavelength allows us to see color. Speed and amplitude are also wave examples. The particle nature of light examples would include the photon and the photoelectric effect.Rate this question:
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- 29.
Which of the following are not examples of the significance of the 'stairstep' on the periodic table?
- A.
It separates metals and non metals.
- B.
It is where the metalloids are located.
- C.
It separates negative ions from positive ions.
- D.
It separates solids from gases.
Correct Answer
D. It separates solids from gases.Explanation
The stairstep on the periodic table separates metals and nonmetals. Not all metals are solids and not all nonmetals are gases.Rate this question:
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- 30.
What causes Periodic Law?
- A.
Increasing atomic mass on the periodic table.
- B.
7 energy levels on the periodic table.
- C.
The repetition of valence electrons.
- D.
The increasing number of neutrons.
Correct Answer
C. The repetition of valence electrons.Explanation
Periodic Law states that there is a repetition of physical and chemical properties when elements are listed in atomic number order. The repetition of the number of valence electrons causes this.Rate this question:
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- 31.
If a piece of metal has a mass of 2.0 g and is placed in a graduated cylinder with 10.0 ml of water. The volume in the graduated cylinder raises to 13.5 ml. What is the density of the piece of metal placed in the graduated cylinder?
- A.
.57 g/ml
- B.
1.75 g/ml
- C.
0.20 g/ml
- D.
0.15 g/ml
Correct Answer
A. .57 g/mlExplanation
Density = mass/volume. The volume of the piece of metal = 13.5 ml - 10.0 ml = 3.5 ml. Density = 2.0g/3.5 ml.Rate this question:
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- 32.
If a neutral atom has an atomic number of 29 and a mass number of 65, how many protons, electrons and neutrons (in order) does it have?
- A.
29, 29, 65
- B.
29, 29, 36
- C.
29,65, 65
- D.
29, 65, 36
Correct Answer
B. 29, 29, 36Explanation
Atomic number = # of protons and in a neutral atom this will also be the number of electrons. Mass number = protons + neutrons. Mass number - atomic number = # of neutrons.Rate this question:
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- 33.
What is the resulting element from alpha decay of U-238?
- A.
Th
- B.
U
- C.
Pu
- D.
Np
Correct Answer
A. ThExplanation
Alpha decay is a helium nucleus and has 2 protons and 2 neutrons. When an element goes through alpha decay the element loses 2 protons and 4 mass units. U would go from 92 protons to 90 protons (Th) and from 238 mass units to 234 amu.Rate this question:
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- 34.
How many electrons can be in the 4th energy level?
- A.
8
- B.
16
- C.
18
- D.
32
Correct Answer
D. 32Explanation
The 4th energy level has 4 sublevels (spdf). The s sublevel holds 2 e-, p holds 6 e-, d holds 10 e- and f holds 14 e- for a total of 32 e- in the 4th energy level.Rate this question:
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- 35.
Which of the following is the electron configuration for Sulfur?
- A.
[Ar] 3s2 3d4
- B.
[Ne] 4s2 3d10 4p4
- C.
[Ne] 3s2 3p4
- D.
1s2 2s2 2p6 3s2 3p6 3d4
Correct Answer
C. [Ne] 3s2 3p4Explanation
Sulfur is in the 3rd energy level and has 4 electrons in the p block.Rate this question:
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- 36.
Which of the following are not true about atomic emission spectra?
- A.
It is caused by the energy released when electrons jump to ground state.
- B.
It can be used to identify elements.
- C.
It is caused by the energy absorbed when electrons jump to ground state.
- D.
Energy released is in the form of multiples of quanta.
Correct Answer
C. It is caused by the energy absorbed when electrons jump to ground state.Explanation
Atomic emission spectra are caused by the energy released when electrons jump to a lower energy level or ground state. This energy release corresponds to specific wavelengths of light, which can be used to identify elements. The energy released is in the form of multiples of quanta, known as photons. Therefore, the statement "It is caused by the energy absorbed when electrons jump to ground state" is not true.Rate this question:
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