Chemistry Mid Term
If 160 mg of technetium-99 is administered for medical diagnosis, how much of the nuclide remains after 24 hours? (t1/2 = 6 hours)
10 mg
If a 10K race is 10.0 km, what is the distance in yards?(Given: 1 yd = 0.914 m)
10,900 yd
Which of the following is equivalent to the volume of a 1.00-L flask?
1000 cm3
What nuclide is produced when N-13 decays by positron emission?
13 6 C
1 atm is equal to:
14.7 psi. 760 mm Hg. Correct! all of the above 760 torr. 101,325 Pa.
Round off the following measurement to three significant digits: 19.945 g.
19.9 g
What is the electron configuration for an aluminum ion, Al3+?
1s2 2s2 2p6
Chlorine (atomic number = 17) has the electronic configuration: ________.
1s22s22p63s23p5
How many significant figures are there in the answer for the following problem?23.1 + 0.5588 + 17 = ?
2
What is the ionic charge for the lead ion in Pb(C2H3O2)2?
2+The correct name for HNO3 is ________.
Add 250.0 mL to 5.00 mL and round off the answer.
255.0 mL
In 1961 a few atoms of a new element were synthesized using the cyclotron at UC Berkeley. Given the balanced nuclear equation, identify the new nuclide. Cf + B → X + 5 n
257 103 Lr
The compound dinitrogen trioxide would have the chemical formula
2O3.
How many unpaired electrons are in an atom of Co in its ground state?
3
Convert 0.003002 to standard scientific notation.
3.002 × 10-3
What is the predicted ionic charge for a Sn ion?
4+
If the number of moles of a gas initially contained in a 2.10 L vessel is doubled, what is the final volume of the gas in liters? (Assume the pressure and temperature remain constant.)
4.20
If an aluminum scuba tank contains compressed air at 2750 psi, what is the pressure expressed in inches of mercury?
5590 in. Hg
Which of the following is the lowest temperature?
57°F
Which electron sublevel follows the 4p sublevel according to increasing energy?
5s
How many propane molecules are in 22.4 liters of C3H8 gas at STP?
6.02 x 1023
Using atomic notation, indicate the isotope having 30 p+, 35 n0, and 30 e-.
65/30 Zn
Divide 6.41 x 10-3 by 8.04 x 107 and express the answer in scientific notation.
7.97 x 10-11
Which is the electron dot structure for nitrogen, N2?
:N:::N:
According to the conservation of mass and energy law, which of the following is true of an atomic fission bomb?
A small amount of mass is converted into energy.
What is the term for the smallest particle that represents an element?
Atom
Which type of natural radiation can penetrate about 1 cm of human flesh and requires wood or aluminum as minimum protective shielding?
Beta
Which of the following are examples of a chemical change?
Both A and B are examples of chemical change.
Atoms of which element, indicated by letter on the periodic table, have the orbital-filling diagram shown below?
C
If a volume of nitrous oxide gas at 45.0 °C decreases from 50.0 mL to 25.0 mL, what is the final Celsius temperature? Assume pressure remains constant.
-114 °C
Liquid krypton boils at 121 K. What is the boiling point on the Celsius scale?
-152 °C
What is the correct Lewis structure for water?
.. H-O-H ..
Which is the electron dot structure of calcium?
.Ca.
How many unpaired electrons are in the ground state electron configuration of calcium?
0
What is the approximate mass and relative charge of a positron?
0 amu and +1
If an automobile airbag inflates in 25 µs, what is the time in seconds?
0.000 025 s
If a silver chain has a mass of 25.0 g, what is the mass in pounds?
0.0551 lb
The density of copper is 8.96 g/cm3. What is the mass in mg of a cube of copper that measures 2.31 mm on each side?
0.110 g
If a 125 mL Erlenmeyer flask weighs 88.5 g, what is the volume in liters?
0.125 L
A balloon filled with 0.500 L of air at sea level is submerged in the water to a depth that produces a pressure of . What is the volume of the balloon at this depth?
0.154 L
A mixture of 0.220 moles CO, 0.350 moles H2 and 0.640 moles He has a total pressure of 2.95 atm. What is the pressure of CO?
0.536 atm
How many moles of helium occupy a volume of 5.00 L at 227.0 °C and 5.00 atm? (R = 0.0821 atm•L/mol•K)
0.609 mol
How many significant digits are in the volume measurement 50,000 mL?
1
Which of the following unit factors is derived from 1 liter = 1.06 quarts?
1 L/1.06 qt
Draw the structural formula for hydrogen fluoride, HF, and state the type of bond in a hydrogen fluoride molecule.
1 single bond
According to the general trends in the periodic table, which of the following is the most electronegative element?
F
Which of the following represents the graph of volume versus Kelvin temperature for a gas at constant pressure?
Graph (d)
Which of the following groups has a predictable ionic charge of two negative?
Group VIA/16
Choose the best Lewis structure for NH4⁺.
H H-N-H H
The proper formula for the hydronium ion is ________.
H3O+
Which orbital-filling diagram represents the ground state of oxygen?
He up down. up down, up, up.
[Kr]5s24d105p5 is the ground state electronic configuration of ________.
I
What is the term for the base unit of length in the metric system?
Meter
Which of the following metric rulers has the least uncertainty?
Ruler D, ± 0.05 cm
Which of the following elements is an example of a semimetal?
Sb
What is the chemical formula for the binary compound composed of Sr2+ and Br- ions?
SrBr2
Which one of the following statements about temperature scales is false?
The Celsius degree is smaller than the Fahrenheit degree.
A certain volume of gas was confined in a rigid container. If the pressure of the gas sample in the container was doubled, what happened to the temperature?
The Kelvin temperature doubled.
According to Boyle's law, what happens to a gas as the volume increases?
The pressure decreases.
Identify triple point.
The temperature and pressure where liquid, solid, and gas are equally stable and are in equilibrium.
Which of the following chemical symbols corresponds to titanium?
Ti
Which electron configuration represents a violation of Hund's rule for an atom in its ground state?
Up down, up down, up down.
Which of the following ions is not isoelectronic with the noble gas argon?
V4+
The definition of a scientific law is:
a number of similar observations generalized into a brief statement summarizing past observations and predicting new ones.
What four elements composed everything in nature according to the beliefs of the ancient Greeks?
air, earth, salt, and water
Which of the following decreases the pressure of a gas?
all of the above
Which of the following describes a substance in the liquid physical state?
all of the above
Which of the following is a branch of chemistry?
all of the above
Which of the following is a halogen?
all of the above
The nighttime and daytime temperatures on Mercury are 13 K and 683 K respectively. The melting point and boiling point of sulfur is 246°F and 832°F. Which of the following statements is true? On Mercury sulfur exists
as both a liquid and a solid.
What is the term for the angle formed by two atoms bonded to the central atom in a molecule?
bond angle
A fuel cell contains hydrogen and oxygen gas. The gases react explosively and the energy converts water to steam. The steam drives a turbine which turns a generator to produce electricity. What two forms of energy are represented by the fuel cell and the turbine?
chemical energy and mechanical energy
What is the term for the study of the composition and properties of matter?
chemistry
Which of the following states that the pressure exerted by a gas is inversely proportional to its volume and directly proportional to its Kelvin temperature?
combined gas law
What is the term for a pure substance that can be broken down into two or more substances by chemical reaction?
compound
Which physical state demonstrates very high kinetic energy?
gaseous state
In comparing gases with liquids, gases have ________ compressibility and ________ density.
greater; smaller
If 0.50 mole H2(g) and 1.0 mole He(g) are compared at standard temperature and pressure, the two gases will:
have equal average molecular kinetic energies
The electronegativity is 2.1 for H and 1.8 for Si. Based on these electronegativities, SiH4 would be expected to
have polar covalent bonds with a partial negative charges on the H atoms.
The nuclear fusion of two deuterium nuclei gives a neutron and nuclide X. Identify nuclide X.
helium-3
What is the term for matter having an indefinite composition and variable properties?
heterogeneous mixture
An aqueous solution of H2S is named
hydrosulfuric acid.
If the temperature of a liquid increases, what happens to its vapor pressure?
increases
The energy of molecules of a gas:
is distributed over a wide range at constant temperature
What is the term for a decimal system of measurement with base units for length, mass, and volume?
metric system
The correct name for HNO3 is ________.
nitric acid
Which of the following best describes the term vacuum?
no gas molecules
Predict which of the following has an ionic bond.
none of the above
Which of the following is an alkaline earth metal?
none of the above
Which of the following is an observed property of liquids?
none of the above
A nuclear power plant uses uranium-235 to convert water to steam. The steam drives a turbine which turns a generator to produce electricity. What are the initial and final forms of energy in this process?
nuclear energy and electrical energy
A glass cylinder contains four liquid layers: mercury (d = 13.6 g/mL), chloroform (d = 1.49 g/mL), water (d = 1.00 g/mL), and ether (d = 0.708 g/mL). If an ice cube (d=0.92 g/mL) is dropped into the cylinder, where does it come to rest?
on top of the water layer
Which of the above fourth-shell orbitals is a 4py orbital?
orbital (a)
What is the term for the study of chemical substances that contain the element carbon?
organic chemistry
Which of the following chemical elements corresponds to the symbol P?
phosphorus
What phase changes occur when the pressure is held constant at 0.25 atm and the temperature increases from 100°C to 300°C?
solid → gas
What is the minimum amount of uranium-235 necessary for a critical mass?
sufficient mass to sustain a chain reaction
What is the geometry around the central atom in the following molecular model of SO32-?
trigonal pyramidal
Molecules can be described as
two or more atoms chemically joined together.
Scientists have analyzed the Dead Sea scrolls by radiocarbon dating and found the activity is about 11.0 dpm per gram of carbon. If carbon-14 has an activity of 15.3 dpm, what is the estimated age of the Dead Sea scrolls? (t1/2 = 5730 years)
~2000 years
