Which answer choice best explains why uranium-238 can be used in power plants to generate electricity?
a) nuclides of uranium-238 decay over time. they release large amounts of energy as their nuclei break apart.
b) nuclides of uranium-238 are extremely stable. they can absorb large amounts of energy without breaking apart, so they rarely need to be replaced
c) because atoms of uranium-238 have many more electrons than protons, they release steady streams of electric current.
d)because atoms of uranium-238 have many more protons than neutrons, they attract large numbers of electrons from the surrounding environment

The correct option is A.

Uranium is a radioactive element, which decays spontaneously. Uranium's decay involves the splitting of the nucleus of uranium, this results in the release of large amount of energy and a new element, which is lighter than uranium. The energy released during this process can be used to generate electricity.

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.