Deck 15: Nuclear Chemistry

Question 1

Which form of radiation will be deflected by an electric field?

A) $\alpha$ particles
B) $\beta$ particles
C) $\gamma$ rays
D) $\alpha$ and $\beta$ particles
E) All three forms of radiation will be deflected by an electric field.

Answer 1

$\alpha$ and $\beta$ particles

Question 2

Which pair represents the same thing?

A) $\alpha$ and $\gamma$ radiation
B) $\beta$ particles and _-1⁰e
C) $\gamma$ rays and a proton
D) $\alpha$ and $\beta$ particles
E) Each pair represents the same thing.

Answer 2

$\beta$ particles and _-1⁰e

Question 3

¹H, ²H, and ³H are best described as ____

A) isotopes
B) isobars
C) isotones
D) compounds
E) alpha particle emitters

Answer 3

isotopes

Question 4

⁹Li, ⁹Be, and ⁹C are best described as ____

A) isotopes
B) isobars
C) isotones
D) compounds
E) covalent

Question 5

⁴⁴P, ⁵⁰Sc, and ⁵²V are best described as ____

A) isotopes
B) isobars
C) isotones
D) compounds
E) p-block elements

Question 6

What is the identity of X in the following equation?
²³⁸U $\rightarrow$ ⁴He + X

A) ²³⁴Pu
B) ²⁴²Ra
C) ²³⁴U
D) ²³⁴Th
E) none of the above

Question 7

What is the identity of X in the following equation?
X $\rightarrow$ ³He + _-1⁰e

A) ³H
B) ²H
C) ⁴Li
D) ²³⁴Th
E) ³Li

Question 8

What is the identity of X in the following equation?
⁶⁵Zn + X $\rightarrow$ ⁶⁵Cu

A) ³H
B) _-1⁰e
C) ₊₁⁰e
D) ₀¹n
E) none of the above

Question 9

The decay of ⁴⁰K to ⁴⁰Ar can be used to determine the age of very old rocks. What mode of radioactive decay is occurring in the conversion of ⁴⁰K to ⁴⁰Ar?

A) $\alpha$ emission
B) electron capture
C) positron emission
D) neutron emission
E) none of the above

Question 10

What is the identity of X in the following equation?
¹⁹F + X $\rightarrow$ ¹⁶O + ⁴He

A) ₁¹p
B) ³H
C) ₊₁⁰e
D) ₀¹n
E) none of the above

Question 11

Element number 43, technetium, is not naturally occurring but is prepared by nuclear reactions for use in medical imaging. The starting material, ⁹⁸Mo, captures one neutron to give a new species X. X decays by electron emission to give species Y which is formed in a metastable state. Y then decays to give ⁹⁹Tc with the emission of a gamma ray. Identify X and Y and write balanced nuclear equations for their formation and decomposition.

Question 12

What is the identity of X in the following equation?
²³⁵U + ₀¹ n $\rightarrow$ ⁹⁹Sr + ¹³⁵Te + 2X

A) ₊₁¹p
B) ³H
C) ₊₁⁰e
D) ₀¹n
E) none of the above

Question 13

Which of the following decay modes will result in an increase in the atomic number of a nuclide?

A) electron emission
B) positron emission
C) $\alpha$ emission
D) $\gamma$ ray emission
E) All of the above decay modes will result in an increase in atomic number.

Question 14

Which of the following nuclides would be the most likely to decay by electron emission?

A) ¹⁷Ne
B) ¹⁸Ne
C) ¹⁹Ne
D) ²⁴Ne
E) They are all equally likely to decay by electron emission.

Question 15

Which of the following nuclides would be the most likely to decay by positron emission?

A) ¹⁹Na
B) ²⁰Na
C) ²¹Na
D) ²²Na
E) They are all equally likely to decay by positron emission.

Question 16

A neutron-poor nuclide can decay by:

A) positron emission
B) electron capture
C) $\alpha$ decay
D) A neutron-poor nuclide cannot decay by any of these routes.
E) A neutron-poor nuclide can decay by any one of these three routes, depending on the mass of the nuclide.

Question 17

Which of the following nuclides would be most likely to be considered neutron-rich?

A) ²⁶Si
B) ⁵⁵Cr
C) ⁶¹Cu
D) ⁴Li
E) ³⁷Ar

Question 18

Which of the following nuclides is most likely to decay by electron capture?

A) ¹²⁵I
B) ³³P
C) ⁸B
D) ¹⁴C
E) ²¹⁰Pb

Question 19

The sum of the mass of 11 protons, 12 neutrons, and 11 electrons will be _____ the mass of a ²³Na atom.

A) greater than
B) smaller than
C) equal to
D) not related to

Question 20

The exact mass of a ¹²C atom does not equal the sum of the mass of 6 protons, 6 neutrons, and 6 electrons because

A) a ¹²C atom has 7 neutrons, not 6.
B) some of the mass of the protons and neutrons is converted to energy when they are combined to form the ¹²C atom.
C) carbon occurs naturally as a mixture of isotopes with slightly different masses.
D) the enthalpy of atom combination of ¹²C is negative.
E) none of the above

Question 21

²²³Rn has a binding energy of 1712.325 MeV. What is the binding energy per nucleon?

A) 19.91076 MeV/nucleon
B) 12.49872 MeV/nucleon
C) 34.83745 MeV/nucleon
D) 1.033238 MeV/nucleon
E) 7.678587 MeV/nucleon

Question 22

The following data is needed for problems


-What is the binding energy in MeV/atpm for a ¹⁴C atom which has an exact mass of 14.003242 amu?

A) between 0 and 30 MeV
B) between 30 and 60 MeV
C) between 60 and 90 MeV
D) between 90 and 120 MeV
E) more than 120 MeV

Question 23

The following data is needed for problems


-What is the exact mass in amu of ³¹P if its binding energy is 8.481184 MeV/nucleon?

A) 30.97377
B) 30.95322
C) 31.25601
D) 32.22563
E) 30.13725

Question 24

The following data is needed for problems


-What is the binding energy per nucleon for ⁶⁰Co? The exact mass of ⁶⁰Co is
59)933822 amu.

A) between 6 and 7 MeV/nucleon
B) between 7 and 8 MeV/nucleon
C) between 8 and 9 MeV/nucleon
D) between 9 and 10 MeV/nucleon
E) more than 10 MeV/nucleon

Question 25

In aging red giant stars, ¹²C undergoes several different fusion reactions, one of which is shown below. What is the energy released in this reaction in MeV?

A) between and 0 and 1 MeV
B) between 1 and 2 MeV
C) between 2 and 3 MeV
D) between 3 and 4 MeV
E) more than 4 MeV

Question 26

All forms of radioactive decay obey a ____ rate law.

A) Zero-order
B) First-order
C) Second-order
D) first or second-order
E) zeroth, first, or second-order

Question 27

A typical rate law for radioactive decay of a nuclide (N) would be:

A) rate = k
B) rate = k(N)^1/2
C) rate = k(N)
D) rate = k(N)²
E) The rate law depends on the mode of radioactive decay.

Question 28

An important component of smoke detectors is the $\alpha$ emitter americium-241 which has a half-life of 432 years. What is the rate constant for the decay of ²⁴¹Am?

A) 432 yr^-1
B) 2.31 x 10^-3 yr^-1
C) 1.60 x 10^-3 yr^-1
D) 0.693 yr^-1
E) none of the above

Question 29

An important component of smoke detectors is the $\alpha$ emitter ²⁴¹Am. The rate constant for the decay of this isotope is 5.1 x 10^-11 dis/s. What is the activity in Curies of the ²⁴¹Am if each detector contains approximately 1.8 x 10^-4 g of the isotope?

Question 30

An important component of smoke detectors is the $\alpha$ emitter ²⁴¹Am. The rate constant for the decay of this isotope is 1.6 x 10^-3 yr^-1. If a smoke detector starts with1.8 x 10^-4 g of the isotope, how long will it take until 1.0 x 10^-4 g of americium remains?

A) 3.7 x 10² years
B) 3.2 x 10² year
C) 4.5 x 10² years
D) 32 years
E) none of the above

Question 31

⁹⁰Sr is a particularly dangerous nuclide formed from the fission of ²³⁵U in atomic bombs because it can readily enter the food chain by replacing calcium in plants or animals. If the rate constant for the decay of ⁹⁰Sr is 0.0274 yr^-1, approximately how long will it take for 99.0% of a sample of ⁹⁰Sr to decay?

A) 168 years
B) 52.0 years
C) 452 years
D) 195 years
E) none of the above

Question 32

The cloth wrappings from a mummified bull found in a pyramid in Dashur, Egypt were dated by ¹⁴C analysis. The wrappings had 78.0% of the radioactivity of living tissue. Approximately how old are the wrappings? The rate constant for the decay of ¹⁴C is 1.21 x 10^-4 yr^-1.

A) less than 500 years old
B) between 500 and 1500 years old
C) between 1500 and 2500 years old
D) between 2500 and 3500 years old
E) more than 3500 years old

Question 33

Which of the following is not an important assumption made in ¹⁴C dating?

A) ¹⁴C is produced in the atmosphere at a more or less constant rate.
B) A carbon atom typically forms four bonds.
C) Carbon atoms circulate among the atmosphere, the oceans, and living organisms faster than they decay.
D) After death, organisms no longer pick up ¹⁴C.
E) All of the above are important assumptions in ¹⁴C dating.

Question 34

Water at various depths in the ocean is recirculated to the surface at different rates. The length of time elapsed since water has been brought up to the surface of the ocean can be estimated by measuring the radioactivity of the ¹⁴C in the CO₂ dissolved in the water. If a sample of water brought up from a depth of 1000 meters displays 88.5% of the radioactivity of water at the surface, how "old" is the water? The rate constant for the decay of ¹⁴C is 1.21 x 10^-4 yr^-1.

A) between 900 and 1100 years
B) between 700 and 900 years
C) between 500 and 700 years
D) between 300 and 500 years
E) less than 300 years

Question 35

The decay of ⁴⁰K to ⁴⁰Ar can be used to determine the age of very old rocks. If moon rocks from the Sea of Tranquility have 12.5% of the estimated original amount of ⁴⁰K, approximately how old are the rocks? ⁴⁰K decays with a rate constant of 5.06 x 10^-10 yr^-1.

A) between 10⁶ and 10⁷ years
B) between 10⁸ and 10⁹ years
C) between 10¹⁰ and 10¹¹ years
D) between 10¹² and 10¹³ years
E) more than 10¹³ years

Question 36

Which of the following is a free radical?

A) H₂O
B) H₃O⁺
C) O₂^-
D) OH^-
E) none of the above

Question 37

The energy required to ionize a single water molecule is 2.02 x 10^-18 J. What wavelength (in nm) photon would deliver this amount of energy?

A) 98.4 nm
B) 115 nm
C) 3.04 x 10¹⁵ nm
D) 536 nm
E) none of the above

Question 38

The first synthesis of element number 116 (ununhexium) was accomplished in 2000 at the Joint Institute for Nuclear Research in Dubna. The Uuh was prepared in the reaction shown below. What is the mass number of the isotope of Uuh prepared?
²⁴⁸Cm + ⁴⁸Ca $\rightarrow$ ₁₁₆Uuh + 4 ¹n

A) 116
B) 296
C) 200
D) 292
E) none of the above

Question 39

Element 110, darnstatdium, was prepared in the reaction shown below. After it was synthesized it decomposed by $\alpha$ decay with a half-life of 270 $\mu$ s. What is the product obtained from the $\alpha$ decay?
²⁰⁸Pb + ⁶²Ni $\rightarrow$ ²⁶⁹Ds + ¹n

A) ²⁶⁵Hs
B) ²⁶⁵Sg
C) ²⁶⁹Hs
D) ¹⁰⁸Bh
E) ²⁶⁷Bh

Question 40

The half-lives for four of the heaviest known elements are given below. Does this data support the theoretical predictions that element 114 should be an "island of stability" in a group of very unstable nuclides? Explain.

Question 41

Nuclear fission is energetically favorable for ______ elements while nuclear fusion is energetically favorable for ______ elements.

A) the heavier, the lighter
B) the lighter, the heavier
C) metallic, lighter
D) heavier, p-block
E) low electronegativity, f-block