CHM 1020 EXAM 4 STUDY GUIDE QUESTIONS WITH
100% PASSED ANSWERS.
The nuclear fission of U−235 can occur by different pathways.
If 2 neutrons and 94Kr36 are produced, what is the other fission product?
Answer - 140/56 Ba
The sun is the most powerful, reliable energy source available on earth. As
photovoltaic cells become more efficient, solar power is becoming a more
realistic option for supplying our energy needs. Fill in the blanks in the
sentences below about photovoltaic cells. Answer - Photovoltaic cells (PVs)
convert light energy into electrical energy.
PVs are made from semiconductors. Two different types are layered - n-type
semiconductors have extra electrons and p-type semiconductors need more
electrons.
Dopants such as gallium or arsenic are added to allow electrons to flow
through the silicon semiconductor.
When a photon with enough energy hits the PV, an "extra" electron is
"knocked" from one layer into a "hole" in the other. The movement of
electrons is an electrical current.
In Chapter 6, neutrons were given by the following symbol:
1n0. An alpha particle (a helium atom) is designated as 4He2 or α. The collision
of 242Cf98 with an alpha particle generates a new isotope and one neutron.
What is the new isotope that is produced in this nuclear reaction? Answer -
245Fm100
, A nuclear power plant functions in much the same way as one which generates
power from fossil fuels. Label the parts of the nuclear power plant in the
diagram. Answer -
After 3 half-lives have passed, what % of the original radioactive isotope
remains? Answer - 12.5
The graph shows the decay of a radioactive sample over days. Select the data
point at three half-lives. Answer - 4 grams after 11.5 days
When fission of Uranium-235 is initiated by a neutron it can result in many
different products. Fill in the correct isotope to complete each reaction.
Answer - 235/92 U + 1/0 n ---> 94/40 Zr + 139/52 Te + 3 1/0 n
235/92 U + 1/0 n ---> 89/34 Se + 144/58 Ce + 3 1/0 n
235/92 U + 1/0 n ---> 90/38 Sr + 144/54 Xe + 2 1/0n
Silicon used for solar panels is found to be 99.9999999% pure. What is the
concentration of impurities in ppb? Answer - 1 ppb
Give the number of protons and neutrons in the nucleus of Tc−99. Answer -
Protons: 43
Neutrons: 55
When fission of Uranium-235 is initiated by a neutron it can result in many
different products. Fill in the correct isotope to complete each reaction.
Answer - 235/92 U + 1/0 n ---> 144/55 Cs + 90/37 Rb + 2 1/0 n
235/92 U + 1/0 n ---> 92/36 Kr + 141/56 Ba + 3 1/0 n
235/92 U + 1/0 n ---> 89/34 Se + 144/58 Ce + 3 1/0 n
100% PASSED ANSWERS.
The nuclear fission of U−235 can occur by different pathways.
If 2 neutrons and 94Kr36 are produced, what is the other fission product?
Answer - 140/56 Ba
The sun is the most powerful, reliable energy source available on earth. As
photovoltaic cells become more efficient, solar power is becoming a more
realistic option for supplying our energy needs. Fill in the blanks in the
sentences below about photovoltaic cells. Answer - Photovoltaic cells (PVs)
convert light energy into electrical energy.
PVs are made from semiconductors. Two different types are layered - n-type
semiconductors have extra electrons and p-type semiconductors need more
electrons.
Dopants such as gallium or arsenic are added to allow electrons to flow
through the silicon semiconductor.
When a photon with enough energy hits the PV, an "extra" electron is
"knocked" from one layer into a "hole" in the other. The movement of
electrons is an electrical current.
In Chapter 6, neutrons were given by the following symbol:
1n0. An alpha particle (a helium atom) is designated as 4He2 or α. The collision
of 242Cf98 with an alpha particle generates a new isotope and one neutron.
What is the new isotope that is produced in this nuclear reaction? Answer -
245Fm100
, A nuclear power plant functions in much the same way as one which generates
power from fossil fuels. Label the parts of the nuclear power plant in the
diagram. Answer -
After 3 half-lives have passed, what % of the original radioactive isotope
remains? Answer - 12.5
The graph shows the decay of a radioactive sample over days. Select the data
point at three half-lives. Answer - 4 grams after 11.5 days
When fission of Uranium-235 is initiated by a neutron it can result in many
different products. Fill in the correct isotope to complete each reaction.
Answer - 235/92 U + 1/0 n ---> 94/40 Zr + 139/52 Te + 3 1/0 n
235/92 U + 1/0 n ---> 89/34 Se + 144/58 Ce + 3 1/0 n
235/92 U + 1/0 n ---> 90/38 Sr + 144/54 Xe + 2 1/0n
Silicon used for solar panels is found to be 99.9999999% pure. What is the
concentration of impurities in ppb? Answer - 1 ppb
Give the number of protons and neutrons in the nucleus of Tc−99. Answer -
Protons: 43
Neutrons: 55
When fission of Uranium-235 is initiated by a neutron it can result in many
different products. Fill in the correct isotope to complete each reaction.
Answer - 235/92 U + 1/0 n ---> 144/55 Cs + 90/37 Rb + 2 1/0 n
235/92 U + 1/0 n ---> 92/36 Kr + 141/56 Ba + 3 1/0 n
235/92 U + 1/0 n ---> 89/34 Se + 144/58 Ce + 3 1/0 n
