I believe it to be g/mol of Calcium carbonate
because to finde mass...u must have grams(g) as units....
it is the only one that have g as units
as for the first answer the avogadros number gives u the number of atoms in one mole of calcium carbonate....
the second one is based on ... At s.t.p one mole of gas occupies 22.4 dm³⇒to find volume
B because once the circuit is burned the lights will all go of
Answer: One formula unit of NaCl consists of one cation, whose chemical symbol is 
and one anion whose chemical symbol is 
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
The cation is formed by the metal sodium which forms and the anion is formed by non metal chlorine which forms .
For a formula unit of sodium chloride, the charges have to be balanced , thus the valencies of ions are exchanged and the neutral compound result. Thus
and combine to form neutral 
There is thermal energy, but temperature is also a measure of the average kinetic energy, so either of those should be acceptable answers for the question.
The accepted model of the atom was changed.
