The element iron, having atomic number 26, is the "crossover point" between fusion and fission. Why?
A) Because all elements heavier than iron are radioactive, implying that they will fission easier than they will fuse.
B) Because of the neutron balance that results from splitting a nucleus.
C) Because for elements lighter than iron, fusion converts nuclear energy to non-nuclear energy, whereas for elements heavier than iron, fission converts nuclear energy to non-nuclear energy.
D) Because neutrons will only split the elements that are heavier than iron.
E) Because for elements lighter than iron, fusion converts non-nuclear energy to nuclear energy, whereas for elements heavier than iron, fission converts non-nuclear energy to nuclear energy.
C
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That Earth ___________, evidence that Earth differentiated
a. rotates slowly b. has an average density that is higher than the density of the crust c. has a no magnetic field d. has a surface that is 75% water e. all of these
It is bright everywhere. You have been able to travel around, and it's clear that you are not inside a star. Yet your surroundings seem as bright as looking directly at the Sun
As you travel around, you notice that you cannot find a single neutral atom anywhere, nor can you find any nucleus besides those of hydrogen and helium. While it is hot (a few thousand degrees Kelvin), it is nowhere near the temperature needed for nuclear fusion. Where are you? A) You are in the planetary nebula that the Sun will form about 5 billion years from now. B) You are in an accretion disk around a supermassive black hole. C) You are in the universe more than 10100 years in the future. D) You are in the universe during its first 380,000 years. E) You are in the central regions of a quasar.
Compared to the Earth, Mars has experienced wild swings in its axis tilt over relatively short time periods. This is because of its
A) proximity to Jupiter and its lack of a large moon B) greater distance from the Sun C) slower rotation rate D) small size
Weight and g: The mass of the Moon is 7.4 × 1022 kg, its radius is 1.74 × 103 km, and it has no atmosphere. What is the acceleration due to gravity at the surface of the Moon? (G = 6.67 × 10-11 N ? m2/kg2)
A. 2.8 × 106 m/s2 B. 9.8 m/s2 C. 4.9 m/s2 D. 1.6 m/s2 E. 0.80 m/s2