If it has a metal and a nonmetal. Not sure if this helps, but I hope it does :)
Answer : The number of sodium ions is equal to the number of formula units of salt.
Explanation : In the given reaction of NaCl the statement which describes it the best is that the number of sodium ions is found to be same along with the formula units in the product side.
+ 
----> NaCl.
Its clear from the equation that one mole of Na and one mole of Cl combines together to give the product, which is one mole of NaCl. The number of ions on both the sides are equal.
Answer:
C8H8O2
Explanation:
The molecular formula of a compound is simply a multiple of the empirical formula as shown below:
Molecular formula => [C4H4O]n
From the question given, we were told that molar mass of the compound is 136g/mol. This implies that:
[C4H4O]n = 136
Now, let us find the value of n in order to obtain the desired result. This is illustrated below:
[C4H4O]n = 136
[(12x4) + (4x1) + 16]n = 136
[48 + 4 + 16]n = 136
68n = 136
Divide both side by the coefficient of n i.e 68
n = 136/68
n = 2
Therefore the molecular formula is
=> [C4H4O]n
=> [C4H4O]2
=> C8H8O2
