Correct Answer: C In nuclear chemistry, a sample of a radioactive substance is said to be critical, or have critical mass, when each fission process induces one other fission process to occur. Increasing the temperature has no effect on nuclear reaction rates. This reaction is thus highly likely occur with no other added energy or reagents. Hence, a value of +0. Since some of the half-reactions occurring appear to be going in the opposite direction of our standard reduction reactions, we need to reverse the sign of the E° of the reactions. For the first 55 minutes, any programmable or graphing calculator may be used, with a few exceptions, and students are not required to erase their calculator memories before and after the exam.
As an aspiring chemist you will be supplied with questions related to the search for solutions to societal concerns and problems, including the depletion of known sources of energy, the extinction of some species through environmental pollution and the struggles of humans to create the conditions for sustainable development. The free-response section emphasizes solving in-depth problems and writing essays where knowledge of which principles to apply and how to apply them is the most important aspect of the solution to these problems. Multiple-Choice Questions For sample multiple-choice questions, refer to the Course Description. Also, 600 torr of N 2 O 5 have decomposed. Question 5 Given the following standard reduction potentials, which reaction would be expected to occur? Although increasing the density of the fissile material 235 U could increase the efficiency of neutron capture, it is not required for the sample to be supercritical.
If a radioactive substance is supercritical, each fission process starts more than one fission process. . The density exceeds that found at ambient temperatures and pressures. For the last 40 minutes, calculators must be put away as students work on the remaining free-response questions. During that time, students will work on three required problems. As you know the study of Chemistry involves an investigation into chemical reactions and processes and documenting the results.
There is less density than found at ambient temperatures and pressures. The rate of production of neutrons exceeds their rate of consumption. Although most calculators are permitted on the free-response section, calculators may not be shared with other students and those with typewriter-style qwerty keyboards will not be permitted on any part of the exam. The radioactive sample need not be pure. Question 2 Which of the following must be true for a sample of supercritical uranium 235 U? There is no choice among the questions; all students must answer all six questions. The multiple-choice questions in Section I cover the breadth of the curriculum.
If N 2 O 5 is added to an evacuated flask to a pressure of 800 torr at 230°C, what is the total pressure in the flask after 14 minutes? The multiple-choice questions in Section I cover the breadth of the curriculum. Calculators are allowed on the free-response section for the first 55 minutes. . . . . .
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