Answer is: mass of sodium nitrate is 21,25 g.
m(H₂O) = 500 g · 1 kg/1000 g = 0,5 kg.
b(solution) = 0,500 m = 0,500 mol/kg.
m(NaNO₃) = ?
b(solution) = n(NaNO₃) ÷ m(H₂O).
n(NaNO₃) = 0,500 mol/kg · 0,5 kg.
n(NaNO₃) = 0,25 mol.
m(NaNO₃) = n(NaNO₃) · M(NaNO₃).
m(NaNO₃) = 0,25 mol · 85 g/mol.
m(NaNO₃) = 21,25 g.
What are the answer choices?
Answer : The current passing between the electrodes is, 
Explanation :
First we have to calculate the charge of sodium ion.

where,
q = charge of sodium ion
n = number of sodium ion = 
e = charge on electron = 
Now put all the given values in the above formula, we get:

Now we have to calculate the charge of chlorine ion.

where,
q' = charge of chlorine ion
n = number of chlorine ion = 
e = charge on electron = 
Now put all the given values in the above formula, we get:

Now we have to calculate the current passing between the electrodes.



Thus, the current passing between the electrodes is, 
The answer would be ethane (C2H4)