A formula unit of an ionic compound Select one:
a. is an independent unit that can be isolated and studied.
O b. is the simplest ratio of ions that balances total charge.
O c. describes the crystal lattice.
O d. all of the above

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b. is the simplest ratio of ions that balances total charge.

Explanation:

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i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.